How to get subarray from array?

How to get subarray from array?

I have var ar = [1, 2, 3, 4, 5] and want some function getSubarray(array, fromIndex, toIndex), that result of call getSubarray(ar, 1, 3) is new array [2, 3, 4].

Solutions/Answers:

Solution 1:

Take a look at Array.slice(begin, end)

var ar  = [1, 2, 3, 4, 5];

var ar2 = ar.slice(1, 3 + 1); // slice from 1..3 - add 1 as the end index is not included

console.log(ar2);

>>[ 2, 3, 4 ]

Solution 2:

for a simple use of slice , use my extension to Array Class :

Array.prototype.subarray=function(start,end){
     if(!end){ end=-1;} 
    return this.slice(start, this.length+1-(end*-1));
}

Then :

var bigArr=["a", "b", "c", "fd", "ze"]

Test1:

bigArr.subarray(1,-1)

< [“b”, “c”, “fd”, “ze”]

Test2:

bigArr.subarray(2,-2)

< [“c”, “fd”]

Test3:

bigArr.subarray(2)

< [“c”, “fd”,”ze”]

Might be easier for developers coming from other language (.i.e: Groovy )

Solution 3:

var array_one = [11, 22, 33, 44,55];
var start = 1;
var end = array_one.length-1
var array_2 = array_one.slice(start, end);
console.log(array_2)

Solution 4:

The question is actually asking for a New array, so I believe a better solution would be to combine Abdennour TOUMI’s answer with a clone function:

function clone(obj) {
    if (null == obj || "object" != typeof obj) return obj;
    var copy = obj.constructor();
    for (var attr in obj) {
        if (obj.hasOwnProperty(attr)) copy[attr] = obj[attr];
    }
    return copy;
}
[http://stackoverflow.com/questions/728360/most-elegant-way-to-clone-a-javascript-object]

With the clone() function, you can now do the following:

Array.prototype.subarray=function(start, end) {
     if(!end){
       end = this.length;
     } 
    var newArray = clone(this);
    return newArray.slice(start, end);
};

Without a copy you will lose your original array.

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Example:

var array = [1,2,3,4,5];
console.log(array.subarray(2)); //print the subarray [3, 4, 5, subarray: function]

console.log(array); //print the original array [1, 2, 3, 4, 5, subarray: function]