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小程序 async await的使用

小程序 async await的使用

作者: Fairy_zhao | 来源:发表于2019-04-17 13:59 被阅读0次

    在要使用async await的文件中,引入这个regeneratorRuntime.js

    promisify.js用于将微信的接口,改成async、await形式。

      const regeneratorRuntime = require("../../libs/regeneratorRuntime.js")
    
      //promisify,用于将微信的接口,改成async、await形式。
      const promisify = require('../../libs/promisify.js')
      const uploadFile = promisify(wx.uploadFile)
    
      uploadImage: async function (node) {
          let options = {
            filePath: node.attrs.src,
            url: this.properties.imageUploadUrl,
            name: this.properties.imageUploadName,
          }
          const res = await uploadFile(options);
          const keyChain = this.properties.imageUploadKeyChain.split('.');
          let url = JSON.parse(res.data);
          keyChain.forEach(key => {
            url = url[key];
          })
          node.attrs.src = url;
          node.attrs._uploaded = true;
          return
        },
    

    regeneratorRuntime.js文件

    /**
     * Copyright (c) 2014-present, Facebook, Inc.
     *
     * This source code is licensed under the MIT license found in the
     * LICENSE file in the root directory of this source tree.
     */
    
    var regeneratorRuntime = (function (exports) {
      "use strict";
    
      var Op = Object.prototype;
      var hasOwn = Op.hasOwnProperty;
      var undefined; // More compressible than void 0.
      var $Symbol = typeof Symbol === "function" ? Symbol : {};
      var iteratorSymbol = $Symbol.iterator || "@@iterator";
      var asyncIteratorSymbol = $Symbol.asyncIterator || "@@asyncIterator";
      var toStringTagSymbol = $Symbol.toStringTag || "@@toStringTag";
    
      function wrap(innerFn, outerFn, self, tryLocsList) {
        // If outerFn provided and outerFn.prototype is a Generator, then outerFn.prototype instanceof Generator.
        var protoGenerator = outerFn && outerFn.prototype instanceof Generator ? outerFn : Generator;
        var generator = Object.create(protoGenerator.prototype);
        var context = new Context(tryLocsList || []);
    
        // The ._invoke method unifies the implementations of the .next,
        // .throw, and .return methods.
        generator._invoke = makeInvokeMethod(innerFn, self, context);
    
        return generator;
      }
      exports.wrap = wrap;
    
      // Try/catch helper to minimize deoptimizations. Returns a completion
      // record like context.tryEntries[i].completion. This interface could
      // have been (and was previously) designed to take a closure to be
      // invoked without arguments, but in all the cases we care about we
      // already have an existing method we want to call, so there's no need
      // to create a new function object. We can even get away with assuming
      // the method takes exactly one argument, since that happens to be true
      // in every case, so we don't have to touch the arguments object. The
      // only additional allocation required is the completion record, which
      // has a stable shape and so hopefully should be cheap to allocate.
      function tryCatch(fn, obj, arg) {
        try {
          return { type: "normal", arg: fn.call(obj, arg) };
        } catch (err) {
          return { type: "throw", arg: err };
        }
      }
    
      var GenStateSuspendedStart = "suspendedStart";
      var GenStateSuspendedYield = "suspendedYield";
      var GenStateExecuting = "executing";
      var GenStateCompleted = "completed";
    
      // Returning this object from the innerFn has the same effect as
      // breaking out of the dispatch switch statement.
      var ContinueSentinel = {};
    
      // Dummy constructor functions that we use as the .constructor and
      // .constructor.prototype properties for functions that return Generator
      // objects. For full spec compliance, you may wish to configure your
      // minifier not to mangle the names of these two functions.
      function Generator() { }
      function GeneratorFunction() { }
      function GeneratorFunctionPrototype() { }
    
      // This is a polyfill for %IteratorPrototype% for environments that
      // don't natively support it.
      var IteratorPrototype = {};
      IteratorPrototype[iteratorSymbol] = function () {
        return this;
      };
    
      var getProto = Object.getPrototypeOf;
      var NativeIteratorPrototype = getProto && getProto(getProto(values([])));
      if (NativeIteratorPrototype &&
        NativeIteratorPrototype !== Op &&
        hasOwn.call(NativeIteratorPrototype, iteratorSymbol)) {
        // This environment has a native %IteratorPrototype%; use it instead
        // of the polyfill.
        IteratorPrototype = NativeIteratorPrototype;
      }
    
      var Gp = GeneratorFunctionPrototype.prototype =
        Generator.prototype = Object.create(IteratorPrototype);
      GeneratorFunction.prototype = Gp.constructor = GeneratorFunctionPrototype;
      GeneratorFunctionPrototype.constructor = GeneratorFunction;
      GeneratorFunctionPrototype[toStringTagSymbol] =
        GeneratorFunction.displayName = "GeneratorFunction";
    
      // Helper for defining the .next, .throw, and .return methods of the
      // Iterator interface in terms of a single ._invoke method.
      function defineIteratorMethods(prototype) {
        ["next", "throw", "return"].forEach(function (method) {
          prototype[method] = function (arg) {
            return this._invoke(method, arg);
          };
        });
      }
    
      exports.isGeneratorFunction = function (genFun) {
        var ctor = typeof genFun === "function" && genFun.constructor;
        return ctor
          ? ctor === GeneratorFunction ||
          // For the native GeneratorFunction constructor, the best we can
          // do is to check its .name property.
          (ctor.displayName || ctor.name) === "GeneratorFunction"
          : false;
      };
    
      exports.mark = function (genFun) {
        if (Object.setPrototypeOf) {
          Object.setPrototypeOf(genFun, GeneratorFunctionPrototype);
        } else {
          genFun.__proto__ = GeneratorFunctionPrototype;
          if (!(toStringTagSymbol in genFun)) {
            genFun[toStringTagSymbol] = "GeneratorFunction";
          }
        }
        genFun.prototype = Object.create(Gp);
        return genFun;
      };
    
      // Within the body of any async function, `await x` is transformed to
      // `yield regeneratorRuntime.awrap(x)`, so that the runtime can test
      // `hasOwn.call(value, "__await")` to determine if the yielded value is
      // meant to be awaited.
      exports.awrap = function (arg) {
        return { __await: arg };
      };
    
      function AsyncIterator(generator) {
        function invoke(method, arg, resolve, reject) {
          var record = tryCatch(generator[method], generator, arg);
          if (record.type === "throw") {
            reject(record.arg);
          } else {
            var result = record.arg;
            var value = result.value;
            if (value &&
              typeof value === "object" &&
              hasOwn.call(value, "__await")) {
              return Promise.resolve(value.__await).then(function (value) {
                invoke("next", value, resolve, reject);
              }, function (err) {
                invoke("throw", err, resolve, reject);
              });
            }
    
            return Promise.resolve(value).then(function (unwrapped) {
              // When a yielded Promise is resolved, its final value becomes
              // the .value of the Promise<{value,done}> result for the
              // current iteration.
              result.value = unwrapped;
              resolve(result);
            }, function (error) {
              // If a rejected Promise was yielded, throw the rejection back
              // into the async generator function so it can be handled there.
              return invoke("throw", error, resolve, reject);
            });
          }
        }
    
        var previousPromise;
    
        function enqueue(method, arg) {
          function callInvokeWithMethodAndArg() {
            return new Promise(function (resolve, reject) {
              invoke(method, arg, resolve, reject);
            });
          }
    
          return previousPromise =
            // If enqueue has been called before, then we want to wait until
            // all previous Promises have been resolved before calling invoke,
            // so that results are always delivered in the correct order. If
            // enqueue has not been called before, then it is important to
            // call invoke immediately, without waiting on a callback to fire,
            // so that the async generator function has the opportunity to do
            // any necessary setup in a predictable way. This predictability
            // is why the Promise constructor synchronously invokes its
            // executor callback, and why async functions synchronously
            // execute code before the first await. Since we implement simple
            // async functions in terms of async generators, it is especially
            // important to get this right, even though it requires care.
            previousPromise ? previousPromise.then(
              callInvokeWithMethodAndArg,
              // Avoid propagating failures to Promises returned by later
              // invocations of the iterator.
              callInvokeWithMethodAndArg
            ) : callInvokeWithMethodAndArg();
        }
    
        // Define the unified helper method that is used to implement .next,
        // .throw, and .return (see defineIteratorMethods).
        this._invoke = enqueue;
      }
    
      defineIteratorMethods(AsyncIterator.prototype);
      AsyncIterator.prototype[asyncIteratorSymbol] = function () {
        return this;
      };
      exports.AsyncIterator = AsyncIterator;
    
      // Note that simple async functions are implemented on top of
      // AsyncIterator objects; they just return a Promise for the value of
      // the final result produced by the iterator.
      exports.async = function (innerFn, outerFn, self, tryLocsList) {
        var iter = new AsyncIterator(
          wrap(innerFn, outerFn, self, tryLocsList)
        );
    
        return exports.isGeneratorFunction(outerFn)
          ? iter // If outerFn is a generator, return the full iterator.
          : iter.next().then(function (result) {
            return result.done ? result.value : iter.next();
          });
      };
    
      function makeInvokeMethod(innerFn, self, context) {
        var state = GenStateSuspendedStart;
    
        return function invoke(method, arg) {
          if (state === GenStateExecuting) {
            throw new Error("Generator is already running");
          }
    
          if (state === GenStateCompleted) {
            if (method === "throw") {
              throw arg;
            }
    
            // Be forgiving, per 25.3.3.3.3 of the spec:
            // https://people.mozilla.org/~jorendorff/es6-draft.html#sec-generatorresume
            return doneResult();
          }
    
          context.method = method;
          context.arg = arg;
    
          while (true) {
            var delegate = context.delegate;
            if (delegate) {
              var delegateResult = maybeInvokeDelegate(delegate, context);
              if (delegateResult) {
                if (delegateResult === ContinueSentinel) continue;
                return delegateResult;
              }
            }
    
            if (context.method === "next") {
              // Setting context._sent for legacy support of Babel's
              // function.sent implementation.
              context.sent = context._sent = context.arg;
    
            } else if (context.method === "throw") {
              if (state === GenStateSuspendedStart) {
                state = GenStateCompleted;
                throw context.arg;
              }
    
              context.dispatchException(context.arg);
    
            } else if (context.method === "return") {
              context.abrupt("return", context.arg);
            }
    
            state = GenStateExecuting;
    
            var record = tryCatch(innerFn, self, context);
            if (record.type === "normal") {
              // If an exception is thrown from innerFn, we leave state ===
              // GenStateExecuting and loop back for another invocation.
              state = context.done
                ? GenStateCompleted
                : GenStateSuspendedYield;
    
              if (record.arg === ContinueSentinel) {
                continue;
              }
    
              return {
                value: record.arg,
                done: context.done
              };
    
            } else if (record.type === "throw") {
              state = GenStateCompleted;
              // Dispatch the exception by looping back around to the
              // context.dispatchException(context.arg) call above.
              context.method = "throw";
              context.arg = record.arg;
            }
          }
        };
      }
    
      // Call delegate.iterator[context.method](context.arg) and handle the
      // result, either by returning a { value, done } result from the
      // delegate iterator, or by modifying context.method and context.arg,
      // setting context.delegate to null, and returning the ContinueSentinel.
      function maybeInvokeDelegate(delegate, context) {
        var method = delegate.iterator[context.method];
        if (method === undefined) {
          // A .throw or .return when the delegate iterator has no .throw
          // method always terminates the yield* loop.
          context.delegate = null;
    
          if (context.method === "throw") {
            if (delegate.iterator.return) {
              // If the delegate iterator has a return method, give it a
              // chance to clean up.
              context.method = "return";
              context.arg = undefined;
              maybeInvokeDelegate(delegate, context);
    
              if (context.method === "throw") {
                // If maybeInvokeDelegate(context) changed context.method from
                // "return" to "throw", let that override the TypeError below.
                return ContinueSentinel;
              }
            }
    
            context.method = "throw";
            context.arg = new TypeError(
              "The iterator does not provide a 'throw' method");
          }
    
          return ContinueSentinel;
        }
    
        var record = tryCatch(method, delegate.iterator, context.arg);
    
        if (record.type === "throw") {
          context.method = "throw";
          context.arg = record.arg;
          context.delegate = null;
          return ContinueSentinel;
        }
    
        var info = record.arg;
    
        if (!info) {
          context.method = "throw";
          context.arg = new TypeError("iterator result is not an object");
          context.delegate = null;
          return ContinueSentinel;
        }
    
        if (info.done) {
          // Assign the result of the finished delegate to the temporary
          // variable specified by delegate.resultName (see delegateYield).
          context[delegate.resultName] = info.value;
    
          // Resume execution at the desired location (see delegateYield).
          context.next = delegate.nextLoc;
    
          // If context.method was "throw" but the delegate handled the
          // exception, let the outer generator proceed normally. If
          // context.method was "next", forget context.arg since it has been
          // "consumed" by the delegate iterator. If context.method was
          // "return", allow the original .return call to continue in the
          // outer generator.
          if (context.method !== "return") {
            context.method = "next";
            context.arg = undefined;
          }
    
        } else {
          // Re-yield the result returned by the delegate method.
          return info;
        }
    
        // The delegate iterator is finished, so forget it and continue with
        // the outer generator.
        context.delegate = null;
        return ContinueSentinel;
      }
    
      // Define Generator.prototype.{next,throw,return} in terms of the
      // unified ._invoke helper method.
      defineIteratorMethods(Gp);
    
      Gp[toStringTagSymbol] = "Generator";
    
      // A Generator should always return itself as the iterator object when the
      // @@iterator function is called on it. Some browsers' implementations of the
      // iterator prototype chain incorrectly implement this, causing the Generator
      // object to not be returned from this call. This ensures that doesn't happen.
      // See https://github.com/facebook/regenerator/issues/274 for more details.
      Gp[iteratorSymbol] = function () {
        return this;
      };
    
      Gp.toString = function () {
        return "[object Generator]";
      };
    
      function pushTryEntry(locs) {
        var entry = { tryLoc: locs[0] };
    
        if (1 in locs) {
          entry.catchLoc = locs[1];
        }
    
        if (2 in locs) {
          entry.finallyLoc = locs[2];
          entry.afterLoc = locs[3];
        }
    
        this.tryEntries.push(entry);
      }
    
      function resetTryEntry(entry) {
        var record = entry.completion || {};
        record.type = "normal";
        delete record.arg;
        entry.completion = record;
      }
    
      function Context(tryLocsList) {
        // The root entry object (effectively a try statement without a catch
        // or a finally block) gives us a place to store values thrown from
        // locations where there is no enclosing try statement.
        this.tryEntries = [{ tryLoc: "root" }];
        tryLocsList.forEach(pushTryEntry, this);
        this.reset(true);
      }
    
      exports.keys = function (object) {
        var keys = [];
        for (var key in object) {
          keys.push(key);
        }
        keys.reverse();
    
        // Rather than returning an object with a next method, we keep
        // things simple and return the next function itself.
        return function next() {
          while (keys.length) {
            var key = keys.pop();
            if (key in object) {
              next.value = key;
              next.done = false;
              return next;
            }
          }
    
          // To avoid creating an additional object, we just hang the .value
          // and .done properties off the next function object itself. This
          // also ensures that the minifier will not anonymize the function.
          next.done = true;
          return next;
        };
      };
    
      function values(iterable) {
        if (iterable) {
          var iteratorMethod = iterable[iteratorSymbol];
          if (iteratorMethod) {
            return iteratorMethod.call(iterable);
          }
    
          if (typeof iterable.next === "function") {
            return iterable;
          }
    
          if (!isNaN(iterable.length)) {
            var i = -1, next = function next() {
              while (++i < iterable.length) {
                if (hasOwn.call(iterable, i)) {
                  next.value = iterable[i];
                  next.done = false;
                  return next;
                }
              }
    
              next.value = undefined;
              next.done = true;
    
              return next;
            };
    
            return next.next = next;
          }
        }
    
        // Return an iterator with no values.
        return { next: doneResult };
      }
      exports.values = values;
    
      function doneResult() {
        return { value: undefined, done: true };
      }
    
      Context.prototype = {
        constructor: Context,
    
        reset: function (skipTempReset) {
          this.prev = 0;
          this.next = 0;
          // Resetting context._sent for legacy support of Babel's
          // function.sent implementation.
          this.sent = this._sent = undefined;
          this.done = false;
          this.delegate = null;
    
          this.method = "next";
          this.arg = undefined;
    
          this.tryEntries.forEach(resetTryEntry);
    
          if (!skipTempReset) {
            for (var name in this) {
              // Not sure about the optimal order of these conditions:
              if (name.charAt(0) === "t" &&
                hasOwn.call(this, name) &&
                !isNaN(+name.slice(1))) {
                this[name] = undefined;
              }
            }
          }
        },
    
        stop: function () {
          this.done = true;
    
          var rootEntry = this.tryEntries[0];
          var rootRecord = rootEntry.completion;
          if (rootRecord.type === "throw") {
            throw rootRecord.arg;
          }
    
          return this.rval;
        },
    
        dispatchException: function (exception) {
          if (this.done) {
            throw exception;
          }
    
          var context = this;
          function handle(loc, caught) {
            record.type = "throw";
            record.arg = exception;
            context.next = loc;
    
            if (caught) {
              // If the dispatched exception was caught by a catch block,
              // then let that catch block handle the exception normally.
              context.method = "next";
              context.arg = undefined;
            }
    
            return !!caught;
          }
    
          for (var i = this.tryEntries.length - 1; i >= 0; --i) {
            var entry = this.tryEntries[i];
            var record = entry.completion;
    
            if (entry.tryLoc === "root") {
              // Exception thrown outside of any try block that could handle
              // it, so set the completion value of the entire function to
              // throw the exception.
              return handle("end");
            }
    
            if (entry.tryLoc <= this.prev) {
              var hasCatch = hasOwn.call(entry, "catchLoc");
              var hasFinally = hasOwn.call(entry, "finallyLoc");
    
              if (hasCatch && hasFinally) {
                if (this.prev < entry.catchLoc) {
                  return handle(entry.catchLoc, true);
                } else if (this.prev < entry.finallyLoc) {
                  return handle(entry.finallyLoc);
                }
    
              } else if (hasCatch) {
                if (this.prev < entry.catchLoc) {
                  return handle(entry.catchLoc, true);
                }
    
              } else if (hasFinally) {
                if (this.prev < entry.finallyLoc) {
                  return handle(entry.finallyLoc);
                }
    
              } else {
                throw new Error("try statement without catch or finally");
              }
            }
          }
        },
    
        abrupt: function (type, arg) {
          for (var i = this.tryEntries.length - 1; i >= 0; --i) {
            var entry = this.tryEntries[i];
            if (entry.tryLoc <= this.prev &&
              hasOwn.call(entry, "finallyLoc") &&
              this.prev < entry.finallyLoc) {
              var finallyEntry = entry;
              break;
            }
          }
    
          if (finallyEntry &&
            (type === "break" ||
              type === "continue") &&
            finallyEntry.tryLoc <= arg &&
            arg <= finallyEntry.finallyLoc) {
            // Ignore the finally entry if control is not jumping to a
            // location outside the try/catch block.
            finallyEntry = null;
          }
    
          var record = finallyEntry ? finallyEntry.completion : {};
          record.type = type;
          record.arg = arg;
    
          if (finallyEntry) {
            this.method = "next";
            this.next = finallyEntry.finallyLoc;
            return ContinueSentinel;
          }
    
          return this.complete(record);
        },
    
        complete: function (record, afterLoc) {
          if (record.type === "throw") {
            throw record.arg;
          }
    
          if (record.type === "break" ||
            record.type === "continue") {
            this.next = record.arg;
          } else if (record.type === "return") {
            this.rval = this.arg = record.arg;
            this.method = "return";
            this.next = "end";
          } else if (record.type === "normal" && afterLoc) {
            this.next = afterLoc;
          }
    
          return ContinueSentinel;
        },
    
        finish: function (finallyLoc) {
          for (var i = this.tryEntries.length - 1; i >= 0; --i) {
            var entry = this.tryEntries[i];
            if (entry.finallyLoc === finallyLoc) {
              this.complete(entry.completion, entry.afterLoc);
              resetTryEntry(entry);
              return ContinueSentinel;
            }
          }
        },
    
        "catch": function (tryLoc) {
          for (var i = this.tryEntries.length - 1; i >= 0; --i) {
            var entry = this.tryEntries[i];
            if (entry.tryLoc === tryLoc) {
              var record = entry.completion;
              if (record.type === "throw") {
                var thrown = record.arg;
                resetTryEntry(entry);
              }
              return thrown;
            }
          }
    
          // The context.catch method must only be called with a location
          // argument that corresponds to a known catch block.
          throw new Error("illegal catch attempt");
        },
    
        delegateYield: function (iterable, resultName, nextLoc) {
          this.delegate = {
            iterator: values(iterable),
            resultName: resultName,
            nextLoc: nextLoc
          };
    
          if (this.method === "next") {
            // Deliberately forget the last sent value so that we don't
            // accidentally pass it on to the delegate.
            this.arg = undefined;
          }
    
          return ContinueSentinel;
        }
      };
    
      // Regardless of whether this script is executing as a CommonJS module
      // or not, return the runtime object so that we can declare the variable
      // regeneratorRuntime in the outer scope, which allows this module to be
      // injected easily by `bin/regenerator --include-runtime script.js`.
      return exports;
    
    }(
      // If this script is executing as a CommonJS module, use module.exports
      // as the regeneratorRuntime namespace. Otherwise create a new empty
      // object. Either way, the resulting object will be used to initialize
      // the regeneratorRuntime variable at the top of this file.
      typeof module === "object" ? module.exports : {}
    ));
    

    promisify.js文件

    module.exports = (api) => {
      return (options, ...params) => {
        return new Promise((resolve, reject) => {
          api(Object.assign({}, options, { success: resolve, fail: reject }), ...params);
        });
      }
    }
    

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          本文标题:小程序 async await的使用

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