循环中的javascript闭包 [英] javascript closure in loop

问题描述

给出以下代码：

  var a = []，i = 0，j = 0; （c）{
 a.push（function（））
 
（i = 0; i <5; i + = 1）{
 
 {
 
 console.log（c）;}）; 
 
}）（i）; 
}; （j = 0; j <5; j + = 1）{a [j]（）;为什么 i 总是会变大1而不是停留 5 ？没有foor循环已经被传递，所以赋给匿名函数的 i 参数应该是 5 ？
解决方案 
如果您从内部闭包引用 i 在所有情况下看到的结果是5。但是，您可以将 i  由值传递给外部函数，该函数被接受为参数 c 。然后，在创建内部闭包的时刻，将 c 的值固定为任何 i 为 / b> 
 
 
考虑更改日志语句： 
 
 
  console。日志（c：+ c +i：+ i）; 
  
您应该看到 c 从0到4（含）以及 i 在所有情况下均为5元。
 
Following code is given:  
var a = [ ], i = 0, j = 0;

for (i = 0; i < 5; i += 1) { 

  (function(c) {
    a.push(function () { 

    console.log(c); });

  })(i);
};

for (j = 0; j < 5; j += 1) { a[j](); } 
Why does i always get bigger by 1 instead of staying 5? Hasn't the foor loop already been passed, so the i parameter given to the anonymous function should be 5?
解决方案
If you referenced i from the inner closure then yes, you would see the result being 5 in all cases.  However, you pass i by value to the outer function, which is accepted as parameter c.  The value of c is then fixed to whatever i was at the moment you created the inner closure.

Consider changing the log statement:
console.log("c:" + c + " i:" + i);
You should see c going from 0 to 4 (inclusive) and i being 5 in all cases.

                        
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