javascript笔记8

javascript面试

//1000代表1000ms

//延时性定时器

for(var i = 0; i < 10; i++) {

  setTimeout(function() {

  console.log(new Date, i);

  }, 10);

}

console.log(new Date, i);

//结果输出：Wed Sep 05 2018 11:42:56 GMT+0800 (中国标准时间) 10

用箭头表示其前后的两次输出之间有 1 秒的时间间隔，而逗号表示其前后的两次输出之间的时间间隔可以忽略，代码实际运行的结果该如何描述？

5 -> 5,5,5,5,5，

5,0,1,2,3,4

for (var i = 0; i < 5; i++) {

(function(j) { // j = i

  setTimeout(function() {

  console.log(new Date, j);

  }, 1000);

})(i);

}

console.log(new Date, i);

var output = function (i) {

setTimeout(function() {

  console.log(new Date, i);

}, 1000);

};

for (var i = 0; i < 5; i++) {

output(i); // 这里传过去的 i 值被复制了

}

console.log(new Date, i);

f = function() {return true;};

g = function() {return false;};

(function(){ 

  if (g() && [] == ![]) { 

      f = function f(){

      return false;

      };

      g = function g() {

      return true;

      };

  }

})();

alert(f());

function DateDemo(){

    var d,s="today is:";

    d = new Date();

    s += d.getMonth()+"/";

    s += d.getDate() + "/";

    s += d.getYear();

    return s;

}

console.log(DateDemo());

var arr = new Array();

arr[0] = "George";

arr[1] = "John";

arr[2] = "Thomas";

arr.unshift("William");

console.log(arr);

//name不能作为一个变量的名字

function func(){

var arr = new Array();

arr[0] = "yuhongxue";

arr[1]="zhanginbo";

arr.unshift("charlie");

// name.unshift("joseph","jane");

// name.unshift("William");

}

console.log(func.name);

console.log(3 + 2 + "7");   //57

console.log("7"+ 3 + 2);    //732

var cloths = ["TShirt", "Pant", "TShirt"];

cloths.pop();

console.log(cloths);