Split array into two arrays

Question

var arr = [\'a\', \'b\', \'c\', \'d\', \'e\', \'f\'];
var point = \'c\';

How can I split the \"arr\" into two arrays based on the \"point\" variabl

Answer 1

var arr = ['a', 'b', 'c', 'd', 'e', 'f'];
var point = 'c';
var i = arr.indexOf(point);
var firstHalf, secondHalf, end, start;

if (i>0) {
  firstHalf = arr.slice(0, i);
  secondHalf = arr.slice(i + 1, arr.length);    
}

//this should get you started. Can you think of what edge cases you should test for to fix? //what happens when point is at the start or the end of the array?

Answer 2

Yet another suggestion:

var segments = arr.join( '' ).split( point ).map(function( part ) {
    return part.split( '' );
});

now segments contains an array of arrays:

[["a", "b"], ["d", "e", "f"]]

and can get accessed like

segments[ 0 ]; // ["a", "b"]
segments[ 1 ]; // ["d", "e", "f"]

Answer 3

if you want to split into equal half; why no simple while loop ?

var arr = ['a', 'b', 'c', 'd', 'e', 'f'];
var c=[];
while(arr.length > c.length){
 c.push(arr.splice(arr.length-1)[0]);
}

Kaboom :).

Answer 4

var arr = ['a', 'b', 'c', 'd', 'e', 'f'];
var point = 'c';
Array.prototype.exists = function(search){
    for (var i=0; i<this.length; i++) {
        if (this[i] == search) return i;
    }
    return false;
} 

if(i=arr.exists(point))
{
    var neewArr=arr.splice(i);
    neewArr.shift(0);

    console.log(arr); // output: ["a", "b"]
    console.log(neewArr); // output: ["d", "e", "f"] 
}​

Here is an example.

Answer 5

Sharing this convenience function that I ended up making after visiting this page.

function chunkArray(arr,n){
     var chunkLength = Math.max(arr.length/n ,1);
     var chunks = [];
     for (var i = 0; i < n; i++) {
         if(chunkLength*(i+1)<=arr.length)chunks.push(arr.slice(chunkLength*i, chunkLength*(i+1)));
     }
     return chunks; 
 }

Sample usage:

chunkArray([1,2,3,4,5,6],2);
//returns [[1,2,3],[4,5,6]]

chunkArray([1,2,3,4,5,6,7],2);
//returns [[1,2,3],[4,5,6,7]]

chunkArray([1,2,3,4,5,6],3);
//returns [[1,2],[3,4],[5,6]]

chunkArray([1,2,3,4,5,6,7,8],3);
//returns [[1,2],[3,4,5],[6,7,8]]

chunkArray([1,2,3,4,5,6,7,8],42);//over chunk
//returns [[1],[2],[3],[4],[5],[6],[7],[8]]

Answer 6

Use indexOf and slice

var arr = ['a', 'b', 'c', 'd', 'e', 'f'];

var indexToSplit = arr.indexOf('c');
var first = arr.slice(0, indexToSplit);
var second = arr.slice(indexToSplit + 1);

console.log({first, second});