Javascript 如何从数组中删除除javascript中的第一个元素之外的所有元素
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How to remove all element from array except the first one in javascript
提问by shadowhunter_077
I want to remove all element from array except the element of array at 0th index
我想从数组中删除除第 0 个索引处的数组元素之外的所有元素
["a", "b", "c", "d", "e", "f"]
Output should be a
输出应该是 a
回答by Satpal
You can set the lengthproperty of the array.
您可以设置length数组的属性。
var input = ['a','b','c','d','e','f'];
input.length = 1;
console.log(input);OR, Use splice(startIndex)method
或，使用splice(startIndex)方法
var input = ['a','b','c','d','e','f'];
input.splice(1);
console.log(input);OR use Array.slicemethod
或使用Array.slice方法
var input = ['a','b','c','d','e','f'];
var output = input.slice(0, 1) // 0-startIndex, 1 - endIndex
console.log(output); 回答by Thank you
This is the headfunction. tailis also demonstrated as a complimentary function.
这就是head功能。tail也被证明是一种补充功能。
Note, you should only use headand tailon arrays that have a known length of 1or more.
请注意，您应该只在已知长度为1或更多的数组上使用head和。tail
// head :: [a] -> a
const head = ([x,...xs]) => x;
// tail :: [a] -> [a]
const tail = ([x,...xs]) => xs;
let input = ['a','b','c','d','e','f'];
console.log(head(input)); // => 'a'
console.log(tail(input)); // => ['b','c','d','e','f']回答by Prateik Darji
array = [a,b,c,d,e,f];
remaining = array[0];
array = [remaining];
回答by Ravikiran kalal
You can use splice to achieve this.
您可以使用 splice 来实现这一点。
Input.splice(0, 1);
More details here . . .http://www.w3schools.com/jsref/jsref_splice.asp
更多细节在这里。. . http://www.w3schools.com/jsref/jsref_splice.asp
回答by Mike Scotty
You can use slice:
您可以使用切片：
var input =['a','b','c','d','e','f'];
input = input.slice(0,1);
console.log(input);Documentation: https://developer.mozilla.org/de/docs/Web/JavaScript/Reference/Global_Objects/Array/slice
文档：https: //developer.mozilla.org/de/docs/Web/JavaScript/Reference/Global_Objects/Array/slice
回答by eisbehr
If you want to keep it in an array, you can use sliceor splice. Or wrap the wirst entry again.
如果要将其保留在 中array，可以使用slice或splice。或者再次包装第一个条目。
var Input = ["a","b","c","d","e","f"];
console.log( [Input[0]] );
console.log( Input.slice(0, 1) );
console.log( Input.splice(0, 1) );回答by Evan Grillo
var input = ["a", "b", "c", "d", "e", "f"];
[input[0]];
// ["a"]
回答by Parthasarathy
var output=Input[0]
It prints the first element in case of you want to filter under some constrains
如果您想在某些限制下进行过滤，它会打印第一个元素
var Input = [ a, b, c, d, e, a, c, b, e ];
$( "div" ).text( Input.join( ", " ) );
Input = jQuery.grep(Input, function( n, i ) {
return ( n !== c );
});
