Remove the element from array A if it exists in array B

JavaScript
1

Hi,
I wonder if there any better method to check if the element in array B exists in array A, then remove it from array A.

var arrA = ['a','b','c','d','e']
var arrB = ['c'];

I copied and modified this code from somewhere I got it online, but not sure if I understand it as it has two for-loops in it…

for(var i=0;i<arrA.length;i++) {
		for(var j=0;j<arrB.length;j++) {
			if(arrB[j] == arrA[i]) {
			var index = arrA.indexOf(arrA[i]);
			}
		}
	}

code to remove element from array A,

if(index >= 0){
		arrA.splice(index,1);
		alert(arrA.join(" "));
		}

Many thanks,
Lau

2

All modern browsers except IE have a useful method to find an item in an array by its value- You can add it to IE without changing the others,
it will come in handy again and again.


Array.prototype.indexOf= 
Array.prototype.indexOf || function(what, index){
	index= index || 0;
	var L= this.length;
	while(index< L){
		if(this[index]=== what) return index;
		++index;
	}
	return -1;
}

This method removes each of its arguments, if present, from the original array

Array.prototype.remove= function(){
	var what, L= arguments.length, ax;
	while(L && this.length){
		what= arguments[--L];
		while((ax= this.indexOf(what))!= -1){
			this.splice(ax, 1);
		}
	}
	return this;
}

to remove all of the elements of one array from another, apply the method:

var a1=[1,2,3,4,5,6], a2=[5,6,7,8,9];
a1.remove.apply(a1,a2);

returned value: (Array) [1,2,3,4];

3

hi, not sure if I understand this code but thanks a lot! :smiley: