Linq has a convenient operator method called Take() to return a given number of elements in anything that implements IEnumerable. Is there anything similar in jQuery for working with arrays?
Or, asked differently: how can I truncate an array in Javascript?
There is a slice method
let arr = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
arr = arr.slice(0, 4);
console.log(arr);Will return the first four elements.
Don't forget to assign it back to your variable if you want to discard the other values.
Note: This is just regular javascript, no need for jquery.
end is NOT included, then @SimonKeep is right, see MDN developer.mozilla.org/en-US/docs/JavaScript/Reference/…
(2 years later...) If you're truly looking to truncate an array, you can also use the length attribute:
var stooges = ["Moe", "Larry", "Shemp", "Curly", "Joe"];
stooges.length = 3; // now stooges is ["Moe", "Larry", "Shemp"]
Note: if you assign a length which is longer than current length, undefined array elements are introduced, as shown below.
var stooges = ["Moe", "Larry", "Shemp"];
stooges.length = 5;
alert(typeof stooges[4]); // alerts "undefined"
EDIT:
As @twhitehead mentioned below, the addition of undefined elements can be avoided by doing this:
var stooges = ["Moe", "Larry", "Shemp"];
stooges.length = Math.min(stooges.length, 5);
alert(stooges.length)// alerts "3"
Array instead of creating a new Array.
stooges.length = Math.min(stooges.length,5);If you're asking how to truncate (modify an array by removing the elements from the end) then use splice:
var a1 = [2,4,6,8];
var a2 = a1.splice(-2,2); // a1=[2,4], a2=[6,8]
If you're asking how to retrieve a subset of an array without modifying the original, then use slice.
var a1 = [2,4,6,8];
var a2 = a1.slice(-2); // a1=[2,4,6,8], a2=[6,8]
Just remember splice modifies, slice accesses. Negative numbers as first arg indicate index from the end of the array.
Set .length property to a lower value.
Official documentation: Array.prototype.length
If you want to selectively pull elements out of an array, you can use the jQuery.grep method.
(from the jQuery docs)
var arr = [ 1, 9, 3, 8, 6, 1, 5, 9, 4, 7, 3, 8, 6, 9, 1 ];
$("div").text(arr.join(", "));
arr = jQuery.grep(arr, function(n, i){
return (n != 5 && i > 4);
});
$("p").text(arr.join(", "));
arr = jQuery.grep(arr, function (a) { return a != 9; });
$("span").text(arr.join(", "));
If you are using a take(3), I'm going to assume the array is originally being defined as the argument 3
const result = new Array(3)
// result = [undefined , undefined , undefined]
If you iterator only returns 2 values, or the values are filtered after the take(3) command and 1 of your values is removed the array would look like
//result = [1 , 1 , undefined]
so to truncate the array of empty elements you can use
result.filter((value) => value !== undefined);
