Question

例如，我有以下代码：

<script>
    function myFunction()
    {
        var x="";
        for (var i=0;i<5;i++)
        {
            x=x+"The number is " + i + "<br>";
        }
        document.getElementById("demo").innerHTML=x;
    }
</script>

我的问题是，为什么x=x+"The number is " + i + " ";代替x="The number is " + i + " ";

Answer 1

第一个代码段x=x+"The number is " + i + " ";将每条新消息附加到字符串x的末尾;第二个x="The number is " + i + " ";只是用新消息替换x。

据推测，第一个输出将被使用，所有输出将立即显示，而不是仅显示最后一行。

Answer 2

一个（x=x+"The number is " + i + " ";）会将输出附加到x并输出：

The number is 0<br>
The number is 1<br>
The number is 2<br>
The number is 3<br>
The number is 4<br>

另一个（x="The number is " + i + " ";）将在每次迭代和输出时替换x：

The number is 4<br>

Answer 3

它将一个字符串附加到另一个字符串，构建一个更长的字符串。

因此，在第一次迭代后，x等于"The number is 0 "，在第二次迭代后，x的值为"The number is 0 The number is 1 "。等等。

Answer 4

When you use :- 
       x=x+"The number is " + i + "<br>"
It will print whole  series numbers 
and When you use :-
        x="The number is " + i + "<br>"
It will print the last value of your series.

Javascript for循环错误

4 个答案: