CODEWITHSUNDEEP
javascriptjquery
Johan
Johan

Reputation: 35223

Remove array of indexes from array

John Resig, creator of jQuery created a very handy Array.remove method that I always use it in my projects:

// Array Remove - By John Resig (MIT Licensed)
Array.prototype.remove = function(from, to) {
  var rest = this.slice((to || from) + 1 || this.length);
  this.length = from < 0 ? this.length + from : from;
  return this.push.apply(this, rest);
};

// Remove the second item from the array
array.remove(1);
// Remove the second-to-last item from the array
array.remove(-2);
// Remove the second and third items from the array
array.remove(1,2);
// Remove the last and second-to-last items from the array
array.remove(-2,-1);

It works great. But I would like to know if it's extendable so that it can take an array of indexes as the first argument?

Otherwise, I will probably make another method that makes use of it:

if (!Array.prototype.removeIndexes) {

    Array.prototype.removeIndexes = function (indexes) {

        var arr = this;

        if (!jQuery)
            throw new ReferenceError('jQuery not loaded');

        $.each(indexes, function (k, v) {

            var index = $.inArray(v, indexes);

            if (index !== -1)
                arr.remove(index);

        });
    };
}

If Array.remove() isn't extendable to fit my needs, what do you think about my other solution above?

Upvotes: 1

Views: 429

Answers (3)

user1233508
user1233508

Reputation:

This version should work. It modifies the original array. If you prefer to return a new array without modifying the original, use the commented out initializer of result and add return result at the end of the function.

Array.prototype.removeIndexes = function(indices) { 
  // make sure to remove the largest index first
  indices = indices.sort(function(l, r) { return r - l; });

  // copy the original so it is not changed
  // var result = Array.prototype.slice.call(this);

  // modify the original array
  var result = this;

  $.each(indices, function(k, ix) {
    result.splice(ix, 1);
  });
}

> [0, 1, 2, 3, 4, 5, 6, 7, 8].removeIndexes([4, 5, 1]);
> [0, 2, 3, 6, 7, 8]

Upvotes: 1

Damien
Damien

Reputation: 8987

I think this is what you are looking for (It works with negative index too) :

if (!Array.prototype.removeIndexes) {

    Array.prototype.removeIndexes = function (indexes) {

        var arr = this;

        if (!jQuery) throw new ReferenceError('jQuery not loaded');

        var offset = 0;

        for (var i = 0; i < indexes.length - 1; i++) {
            if (indexes[i] < 0)
                indexes[i] = arr.length + indexes[i];
            if (indexes[i] < 0 || indexes[i] >= arr.length)
                throw new Error('Index out of range');
        }

        indexes = indexes.sort();

        for (var i = 0; i < indexes.length - 1; i++) {
            if (indexes[i + 1] == indexes[i])
                throw new Error('Duplicated indexes');
        }


        $.each(indexes, function (k, index) {
            arr.splice(index - offset, 1);
            offset++;
        });
        return arr;
    };
}

var a = ['a', 'b', 'c', 'd', 'e', 'f'];
var ind = [3, 2, 4];

a.removeIndexes(ind);

console.log(a.join(', '));
// returns : a, b, f

See fiddle

Upvotes: 1

Atif
Atif

Reputation: 10880

How about 

Array.prototype.remove = function (indexes) {
    if(indexes.prototype.constructor.name == "Array") {
        // your code to support indexes
    } else {
        // the regular code to remove single or multiple indexes
    }

};

Upvotes: 0

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