how to do a "flat push" in javascript?

user_288190 0
Viewed 15257

I want to push all individual elements of a source array onto a target array,

target.push(source);

puts just source's reference on the target list.

In stead I want to do:

for (i = 0; i < source.length; i++) {
    target.push(source[i]);
}

Is there a way in javascript to do this more elegant, without explicitly coding a repetition loop?

And while I'm at it, what is the correct term? I don't think that "flat push" is correct. Googling did not yield any results as source and target are both arrays.

flatten push arrays javascript
4 Answers

The easier way to do this. 

   var arr1 = [1,2,3] 
   var arr2 = [4,5,6] 
   arr1.push(...arr2) //arr1 now contains [1,2,3,4,5,6]
user_64820870

You can simply use spread syntax:

var arr1 = [0, 1, 2];
var arr2 = [3, 4, 5];

arr1 = [...arr1, ...arr2];
    // [0, 1, 2, 3, 4, 5]

Alternatively:

var arr1 = ['a', 'b', 'c'];
var arr2 = [1, 2, 3, ...arr1];
        // [1, 2, 3, 'a', 'b', 'c']

Demo:

var arr1 = [0, 1, 2];
var arr2 = [3, 4, 5];

arr1 = [...arr1, ...arr2];
console.log(arr1);

user_59336560
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