IndexOf array of several arrays with javascript

Question

I have an array this way :

var array = [ [1,2] , [2,2,2] , 3 , [3,4] ];

So I want to use indexOf to splice an element.

Example :

var index = array.indexOf( [2,2,2] );
array.splice(index, 1)

Expect =>

array = [ [1,2] , 3 , [3,4] ]

But the problem is that index return -1 (false value).. How to fix that?

Answer 1

The problem is, you have two arrays with the same primitives, but the arrays are not equal.

The comparing works with the object and not with the values inside.

 console.log([2, 2, 2] === [2, 2, 2]); // false var array = [2, 2, 2]; console.log(array === array); // true 

If you search for the same array with the same reference to the object, then you get the right index.

 var search = [2, 2, 2], // array to serach for array = [[1, 2], search, 3, [3, 4]], // array with search array index = array.indexOf(search); // get the index array.splice(index, 1); console.log(array); // [[1, 2], 3, [3, 4]] 

In ES5, you could search for the index and use a stringified version of the search object for checking with Array#some .

 var array = [[1, 2], [2, 2, 2], 3, [3, 4]], search = [2, 2, 2], index = -1; array.some(function(a, i) { if (JSON.stringify(a) === JSON.stringify(search)) { index = i; return true; } }); if (index !== -1) { array.splice(index, 1); } console.log(array); 

ES6 with Array#findIndex

 var array = [[1, 2], [2, 2, 2], 3, [3, 4]], search = [2, 2, 2], index = array.findIndex(a => JSON.stringify(a) === JSON.stringify(search)); if (index !== -1) { array.splice(index, 1); } console.log(array) 

Answer 2

If you can use a library, you can use the lodash library that exposes a reject function.

Here is a snippet:

 var array = [ [1,2] , [2,2,2] , 3 , [3,4] ]; var result = _.reject(array, [2,2,2]); console.log(result); 

 <script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.4/lodash.min.js"></script> 

Answer 3

var array = [[1, 2], [2, 2, 2], 3, [3, 4]];
var index = array.findIndex(a => JSON.stringify(a) === "[2,2,2]");
    alert(index);
if (index > -1) {
    array.splice(index, 1);
}
alert(array)

Hope this helps!

Answer 4

indexOf doesn't work because it uses strict equality, so you can't find an array within an array unless you have a reference to the array you're trying to find.

As an alternative, you can use a plain old ed 3 for loop and compare stringified values:

 var array = [ [1,2] , [2,2,2] , 3 , [3,4] ]; function findIndex(arr, value) { for ( var i=0, value=String(value), iLen=arr.length; i<iLen; i++) { if (String(arr[i]) == value) return i; } return -1; } console.log(findIndex(array, [2,2,2])); // 1