Javascript javascript创建给定大小的空数组
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javascript create empty array of a given size
提问by gus
in javascript how would I create an empty array of a given size
在 javascript 中，我将如何创建一个给定大小的空数组
Psuedo code:
伪代码：
X = 3;
createarray(myarray, X, "");
output:
输出：
myarray = ["","",""]
采纳答案by mariocatch
var arr = new Array(5);
console.log(arr.length) // 5
回答by stpoa
1)To create new array which, you cannot iterate over, you can use array constructor:
1）要创建不能迭代的新数组，可以使用数组构造函数：
Array(100)or new Array(100)
Array(100)或者 new Array(100)
2)You can create new array, which can be iterated overlike below:
2）您可以创建新数组，可以像下面这样迭代：
a)All JavaScript versions
a)所有 JavaScript 版本
- Array.apply:
Array.apply(null, Array(100))
- 数组.应用：
Array.apply(null, Array(100))
b)From ES6 JavaScript version
b)从 ES6 JavaScript 版本开始
- Destructuring operator:
[...Array(100)] - Array.prototype.fill
Array(100).fill(undefined) - Array.from
Array.from({ length: 100 })
- 解构运算符：
[...Array(100)] - 数组.prototype.fill
Array(100).fill(undefined) - 数组.from
Array.from({ length: 100 })
You can map over these arrays like below.
您可以像下面这样映射这些数组。
Array(4).fill(null).map((u, i) => i)[0, 1, 2, 3][...Array(4)].map((u, i) => i)[0, 1, 2, 3]Array.apply(null, Array(4)).map((u, i) => i)[0, 1, 2, 3]Array.from({ length: 4 }).map((u, i) => i)[0, 1, 2, 3]
Array(4).fill(null).map((u, i) => i)[0, 1, 2, 3][...Array(4)].map((u, i) => i)[0, 1, 2, 3]Array.apply(null, Array(4)).map((u, i) => i)[0, 1, 2, 3]Array.from({ length: 4 }).map((u, i) => i)[0, 1, 2, 3]
回答by andrewkslv
We use Array.from({length: 500})since 2017.
我们Array.from({length: 500})从 2017 年开始使用。
回答by guest271314
Try using whileloop, Array.prototype.push()
尝试使用while循环，Array.prototype.push()
var myArray = [], X = 3;
while (myArray.length < X) {
myArray.push("")
}
Alternatively, using Array.prototype.fill()
或者，使用 Array.prototype.fill()
var myArray = Array(3).fill("");
回答by 7vujy0f0hy
In 2018 and thenceforth we shall use [...Array(500)]to that end.
在 2018 年及以后，我们将[...Array(500)]为此目的使用。
回答by jeffdill2
If you want an empty array of undefinedelements, you could simply do
如果你想要一个空的undefined元素数组，你可以简单地做
var whatever = new Array(5);
this would give you
这会给你
[undefined, undefined, undefined, undefined, undefined]
and then if you wanted it to be filled with empty strings, you could do
然后如果你想用空字符串填充它，你可以这样做
whatever.fill('');
which would give you
这会给你
["", "", "", "", ""]
And if you want to do it in one line:
如果你想在一行中完成：
var whatever = Array(5).fill('');
