The best way to remove array element by value

I have an array like this

arr = ["orange","red","black","white"]

I want to augment the array object defining a deleteElem() method which acts like this:

arr2 = arr.deleteElem("red"); // ["orange","black","white"] (with no hole)

What is the best way to accomplish this task using just the value parameter (no index)?

Here's how it's done:

var arr = ["orange","red","black","white"];
var index = arr.indexOf("red");
if (index >= 0) {
  arr.splice( index, 1 );
}

This code will remove 1 occurency of "red" in your Array.

Back when I was new to coding I could hardly tell what splice was doing, and even today it feels less readable.

But readability counts.

I would rather use the filter method like so:

arr = ["orange","red","black","white","red"]

arr = arr.filter(val => val !== "red");

console.log(arr) // ["orange","black","white"]

Note how all occurrences of "red" are removed from the array.

From there, you can easily work with more complex data such as array of objects.

arr = arr.filter(obj => obj.prop !== "red");

There is an underscore method for this, http://underscorejs.org/#without

arr = ["orange","red","black","white"];

arr = _.without(arr, "red");

The trick is to go through the array from end to beginning, so you don't mess up the indices while removing elements.

var deleteMe = function( arr, me ){
   var i = arr.length;
   while( i-- ) if(arr[i] === me ) arr.splice(i,1);
}

var arr = ["orange","red","black", "orange", "white" , "orange" ];

deleteMe( arr , "orange");

arr is now ["red", "black", "white"]

My approach, let's see what others have to say. It supports an "equals" method as well.

 // Remove array value
 // @param {Object} val
 Array.prototype.removeByValue = function (val) {
    for (var i = 0; i < this.length; i++) {
       var c = this[i];
       if (c == val || (val.equals && val.equals(c))) {
          this.splice(i, 1);
          break;
       }
    }
 };

Read https://stackoverflow.com/a/3010848/356726 for the impact on iterations when using prototype with Array.

Array.prototype.deleteElem = function(val) {
    var index = this.indexOf(val); 
    if (index >= 0) this.splice(index, 1);
    return this;
}; 
var arr = ["orange","red","black","white"];
var arr2 = arr.deleteElem("red");

Or simply check all items, create a new array with non equal and return it.

var arr = ['orange', 'red', 'black', 'white'];

console.info('before: ' + JSON.stringify(arr));

var deleteElem = function ( val ) {
    var new_arr = [];
    for ( var i = 0; i < this.length; i++ ) {
        if ( this[i] !== val ) {
            new_arr.push(this[i]);
        }
    }
    return new_arr;
};

arr = deleteElem('red');

console.info('after: ' + JSON.stringify(arr));

http://jsfiddle.net/jthavn3m/

The best way is to use splice and rebuild new array, because after splice, the length of array does't change.

Check out my answer:

function remove_array_value(array, value) {
    var index = array.indexOf(value);
    if (index >= 0) {
        array.splice(index, 1);
        reindex_array(array);
    }
}
function reindex_array(array) {
   var result = [];
    for (var key in array) {
        result.push(array[key]);
    }
    return result;
}

example:

var example_arr = ['apple', 'banana', 'lemon'];   // length = 3
remove_array_value(example_arr, 'banana');

banana is deleted and array length = 2

If order the array (changing positions) won't be a problem you can solve like:

var arr = ["orange","red","black","white"];
arr.remove = function ( item ) {
  delete arr[item];
  arr.sort();
  arr.pop();
  console.log(arr);
}

arr.remove('red');

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>

Here you go:

arr.deleteElem = function ( val ) {
    for ( var i = 0; i < this.length; i++ ) {
        if ( this[i] === val ) {
            this.splice( i, 1 );
            return i;
        }
    }
};

Live demo: http://jsfiddle.net/4vaE2/3/

The deleteElem method returns the index of the removed element.

var idx = arr.deleteElem( 'red' ); // idx is 1