javascript - remove array element on condition

Question

I was wondering how I\'d go about implementing a method in javascript that removes all elements of an array that clear a certain condition. (Preferably without using jQuery)

Answer 1

I love these kinds of questions and just a different version from me too... :)

Array.prototype.removeIf = function(expression) {
   var res = [];
    for(var idx=0; idx<this.length; idx++)
    {
      var currentItem = this[idx];
        if(!expression(currentItem))
        {
            res.push(currentItem);
        }
    }
    return res;
}

ar = [ 1, 2, 3, 4 ];
var result = ar.removeIf(expCallBack);


console.log(result);
function expCallBack(item)
{
    return item > 3;
}

Answer 2

simply write the following example if condition could work on object properties as well

var ar = [ {num:1, str:"a"}, {num:2, str:"b"}, {num:3, str:"c"} ];
var newArray = [];
for (var i = 0, len = ar.length; i<len; i++) {
        if (ar[i].str == "b") 
        {newArray.push(ar[i]);};
 };
console.log(newArray);

See the example Live Example

Answer 3

You can use Array filter method.

The code would look like this:

ar = [1, 2, 3, 4];
ar = ar.filter(item => !(item > 3));
console.log(ar) // [1, 2, 3]

Answer 4

You can use Array.filter(), which does the opposite:

ar.filter(function(item, idx) {
    return item <= 3;
});

Answer 5

You can use lodash.remove

var array = [1, 2, 3, 4];
var evens = _.remove(array, function(n) {
  return n % 2 == 0;
});

console.log(array);
// => [1, 3]

console.log(evens);
// => [2, 4]

Answer 6

Make it a one-liner with arrow function:

ar = ar.filter(i => i > 3);