Confusion with javascript array.splice()

javascript array-splice
Trolleymusic picture Trolleymusic · Sep 22, 2011 · Viewed 11.3k times · Source

I'm really confused about this.

My understanding was that array.splice(startIndex, deleteLength, insertThing) would insert insertThing into the result of splice() at startIndex and delete deleteLength's worth of entries? ... so:

var a = [1,2,3,4,5];
var b = a.splice(1, 0, 'foo');
console.log(b);

Should give me:

[1,'foo',2,3,4,5]

And

console.log([1,2,3,4,5].splice(2, 0, 'foo'));

should give me

[1,2,'foo',3,4,5]

etc.

But for some reason it's giving me just an empty array? Take a look: http://jsfiddle.net/trolleymusic/STmbp/3/

Thanks :)

Answer

Pointy picture Pointy · Sep 22, 2011

The "splice()" function returns not the affected array, but the array of removed elements. If you remove nothing, the result array is empty.

Related questions

Deleting array elements in JavaScript - delete vs splice

What is the difference between using the delete operator on the array element as opposed to using the Array.splice method? For example: myArray = ['a', 'b', 'c', 'd']; delete myArray[1]; // or myArray.splice (1, 1); Why even have the splice method if …

Read More
angularjs forEach and splice

I have an array like this: $scope.emails = [ {"key":"Work","value":"[email protected]"}, {"key":"","value":""}, {"key":"Work","value":"[email protected]"} {"key":"","value":""}]; So, I want to remove empty emails but angular forEach method removing only one object that …

Read More
How to remove all element from array except the first one in javascript

I want to remove all element from array except the element of array at 0th index ["a", "b", "c", "d", "e", "f"] Output should be a

Read More