从数组填充另一个数组 - Javascript
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Populating another array from array - Javascript
提问by ina
Very simple thing I am trying to do in JS (assign the values of one array to another), but somehow the array bar's value doesn't seem affected at all.
我试图在 JS 中做的非常简单的事情（将一个数组的值分配给另一个），但不知何故，数组bar的值似乎根本不受影响。
The first thing I tried, of course, was simply bar = ar;-- didn't work, so I tried manually looping through... still doesn't work.
当然，我尝试的第一件事很简单bar = ar;——没有用，所以我尝试手动循环……仍然不起作用。
I don't grok the quirks of Javascript! Please help!!
我不理解 Javascript 的怪癖！请帮忙！！
var ar=["apple","banana","canaple"];
var bar;
for(i=0;i<ar.length;i++){
bar[i]=ar[i];
}
alert(ar[1]);
And, here is the fiddle: http://jsfiddle.net/vGycZ/
而且，这是小提琴：http: //jsfiddle.net/vGycZ/
(The above is a simplification. The actual array is multidimensional.)
（以上是简化。实际数组是多维的。）
回答by CMS
Your code isn't working because you are not initializing bar:
您的代码不起作用，因为您没有初始化bar：
var bar = [];
You also forgot to declare your ivariable, which can be problematic, for example if the code is inside a function, iwill end up being a global variable (always use var:).
您还忘记声明您的i变量，这可能会出现问题，例如，如果代码在函数内部，i最终将成为全局变量（始终使用var:）。
But, you can avoid the loop, simply by using the slicemethod to create a copy of your first array:
但是，您可以避免循环，只需使用该slice方法创建第一个数组的副本：
var arr = ["apple","banana","canaple"];
var bar = arr.slice();
回答by Pranay Rana
copy-or-clone-javascript-array-object
var a = [ 'apple', 'orange', 'grape' ];
b = a.slice(0);
回答by Luis Cabrera Benito
In ES6 you can use Array.from:
在 ES6 中，您可以使用Array.from：
var ar = ["apple","banana","canaple"];
var bar = Array.from(ar);
alert(bar[1]); // alerts 'banana'
回答by Daniel Vassallo
You have two problems:
你有两个问题：
First you need to initialize baras an array:
首先你需要初始化bar为一个数组：
var bar = [];
Then arrshould be arin here:
那么arr应该ar在这里：
for(i=0;i<arr.length;i++){
for(i=0;i<arr.length;i++){
Then you'll get alerted your banana :)
然后你会收到通知你的香蕉:)
回答by Arghya C
With ES6+ you can simply do this
使用ES6+ 你可以简单地做到这一点
const original = [1, 2, 3];
const newArray = [...original];
The documentation for spread syntax is here
传播语法的文档在这里
To check, run this small code on dev console
要检查，请运行此小代码 dev console
const k = [1, 2];
const l = k
k === l
> true
const m = [...k]
m
>?[1, 2]
k === m
> false
回答by Codler
You have misspelled variable ar Try this
你拼错了变量 ar 试试这个
for(i=0;i<ar.length;i++){
bar[i]=ar[i];
}
alert(ar[1]);
回答by Artem Barger
The problem probably here in the for loop statement:
问题可能出现在 for 循环语句中：
for(i=0;i<ar.length;i++){
bar[i]=ar[i];
}
alert(ar[1]);
You need to fix to ar.lengthinstead of arr.length.And it's better to initialize bar as: var bar = [].
您需要修复 toar.length而不是arr.length.And 最好将 bar 初始化为：var bar = []。
回答by slebetman
In your code, the variable arrin the for loop is not the same as your original array ar: you have one too many r.
在您的代码中，arrfor 循环中的变量与您的原始数组不同ar：您有一个太多的r.
