for..in和for each..in在javascript中有什么区别？ [英] What is the difference between for..in and for each..in in javascript?

问题描述

for ... in和for each ... in语句在javascript中有什么区别？
是否有细微的差别，我不知道或是相同的，每个浏览器有不同的名称？

解决方案 div

for each ... in 在指定对象属性的所有值上迭代指定变量。

例子：

  var sum = 0; 
 var obj = {prop1：5，prop2：13，prop3：8}; 
（obj中的var项）{
 sum + = item; 
} 
 print（sum）; //打印26，即5 + 13 + 8 
  

来源

for ... in以任意顺序遍历对象的所有属性指定的变量。

例子：

  function show_props（obj，objName）{
 var result =; 
 for（var i in obj）{
 result + = objName +。 + i +=+ obj [i] +\\\
; 
} 
返回结果; 
} 
  

来源

---

注意03.2013，对于循环中的每个... 都是已弃用。 MDN推荐的新语法是 for ... 。

What is the difference between for..in and for each..in statements in javascript? Are there subtle difference that I don't know of or is it the same and every browser has a different name for it?

解决方案

"for each...in" iterates a specified variable over all values of the specified object's properties.

Example:

var sum = 0;
var obj = {prop1: 5, prop2: 13, prop3: 8};
for each (var item in obj) {
  sum += item;
}
print(sum); // prints "26", which is 5+13+8

Source

"for...in" iterates a specified variable over all properties of an object, in arbitrary order.

Example:

function show_props(obj, objName) {
   var result = "";
   for (var i in obj) {
      result += objName + "." + i + " = " + obj[i] + "\n";
   }
   return result;
}

Source

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Note 03.2013, for each... in loops are deprecated. The 'new' syntax recommended by MDN is for... of.

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