javascript es6数组特征[... data，0]“扩展运算符” [英] javascript es6 array feature [...data, 0] "spread operator"

问题描述

  const addCounter =（list ）=> {
 return [... list，0]; //这是我现在失去的一点[...列表，0] 
} 
  

显然以上是相同的。

  const addCounter =（list）=> {
 return list.concat（[0]）; 
} 
  

任何建议或解释都非常感激。

解决方案

...列表正在使用 spread operator 来传播元素 list 。我们假设列表是 [1，2，3] 。因此 [... list，0] 变成：

  [1 ，2，3，0] 
  

与列表相同的结果.concat（[0]）;

这不是ES6中数组的一个特性，它只是用于数组连接。它有其他用途。阅读更多 MDN ，或参见< a href =https://stackoverflow.com/questions/20541339/usage-of-rest-parameter-and-spread-operator-in-javascript>此问题。

I am come up with this in one of the example code and i am completely lost.

const addCounter = (list) => {
    return [...list, 0];  // This is the bit i am lost i now about [...list, 0]
}

Apparently the above is equal the following.

const addCounter = (list) => {
    return list.concat([0]);
}

Any suggestion or explain is much appreciated.

解决方案

...list is using the spread operator to spread the elements of list. Let's assume the list is [1, 2, 3]. Therefore [...list, 0] becomes:

[1, 2, 3, 0]

Which has the same result as doing list.concat([0]);

This is not a feature of the array in ES6, it's just been used for array concatenation. It has other uses. Read more on MDN, or see this question.

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