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获取平均数之Function.prototype.call()、

获取平均数之Function.prototype.call()、

作者: vscode_pan_dev | 来源:发表于2018-10-08 19:12 被阅读0次

    // = > 1、常规方法:

      function sum(arg) {
        var newary = [];
    
        //类数组转换为数组
        if (arg instanceof Array){
            console.log("传参方式是数组");
            for (var i = 0; i < arg.length; i++) {
                newary.push(arg[i]);
            }
        }else {
            console.log('传参方式是多个数字');
            for (var i = 0; i < arguments.length; i++) {
                newary.push(arguments[i]);
            }
        }
    
        //数组从小到打排序
        newary.sort(function (a,b) {
            return a-b;
        });
        //删除数组开头的最小项
        newary.shift();
        //删除数组末尾最大项
        newary.pop();
       //循环求和
        var result  = 0;
        for (var i = 0; i < newary.length; i++) {
            result += newary[i];
        }
        //求平均数,并返回结果
        return Math.round(result/newary.length);
    }
    
    var result1 = sum(156,423,90,5,24,66,450,25,4,86,76,64,5,88,63,33,42,34,46,19,48,35,70);
    console.log(result1);  // => 71.33333333333333
    
    var arr = [1,2,3,4,5,6,7,8,9];
    var result2 = sum(arr);
    console.log(result2);    // => 5
    

    // = > 常规方法改进:1.0版

       function sum(arg) {
        //类数组转换为数组
        if (arg instanceof  Array) {
            var newary =  Array.prototype.slice.apply(arg);
        }else {
            var newary =  Array.prototype.slice.call(arguments);
        }
        //数组从小到打排序
        newary.sort(function (a,b) {
            return a-b;
        });
        //删除数组开头的最小项
        newary.shift();
        //删除数组末尾最大项
        newary.pop();
    
        //求平均数,并返回结果
        return (eval(newary.join('+'))/newary.length).toFixed(2)
    }
    
    var result1 = sum(156,423,90,5,24,66,450,25,4,86,76,64,5,88,63,33,42,34,46,19,48,35,70);
    console.log(result1);    // = >71.33
    
    var arr = [1,2,3,4,5,6,7,8,9];
    var result2 = sum(arr);
    console.log(result2);      // = >5.00
    

    // = > 常规方法改进:2.0版

       function sum(arg) {
        console.log(arg instanceof Array);
        if (!(arg instanceof Array)) {
            console.log("如果不是数组,执行下面语句");
            var newary = Array.prototype.sort.call(arguments, function (a,b) {return a - b;});
        } else {
            console.log("如果是数组,执行下面语句");
            var newary = Array.prototype.sort.apply(arguments[0],function (a,b) { return a-b;});
        }
        //删除数组开头的最小项
        Array.prototype.shift.call(newary);
        //删除数组末尾最大项
        Array.prototype.pop.call(newary);
        //求平均数,并返回结果
        return (eval([].join.call(newary,'+')) / newary.length).toFixed(2)
    }
    
    var result1 = sum(156, 423, 90, 5, 24, 66, 450, 25, 4, 86, 76, 64, 5, 88, 63, 33, 42, 34, 46, 19, 48, 35, 70);
    console.log(result1);    // => 71.33
    
    var arr = [1,2,3,4,5,6,7,8,9];
    var result2 = sum(arr);
    console.log(result2);    //=>5.00
    

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