将数组拆分为两个数组

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" variable, like:

['a', 'b']

and

['d', 'e', 'f']

Answer 1

var arr2 = ['a', 'b', 'c', 'd', 'e', 'f'];
arr = arr2.splice(0, arr2.indexOf('c'));

To remove 'c' from arr2:

arr2.splice(0,1);

arr contains the first two elements and arr2 contains the last three.

This makes some assumptions (like arr2 will always contain the 'point' at first assignment), so add some correctness checking for border cases as necessary.

Answer 2

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}); 

Answer 3

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 4

Try this one:

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

var idx = arr.indexOf(point);

arr.slice(0, idx) // ["a", "b"]
arr.slice(idx + 1) // ["d", "e", "f"]

Answer 5

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 6

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 7

When splitting the array you are going to want to create two new arrays that will include what you are splitting, for example arr1 and arr2. To populate this arrays you are going to want to do something like this:

var arr1, arr2; // new arrays
int position = 0; // start position of second array
   for(int i = 0; i <= arr.length(); i++){
       if(arr[i] = point){ //when it finds the variable it stops adding to first array
           //starts adding to second array
            for(int j = i+1; j <= arr.length; j++){
               arr2[position] = arr[j];
               position++; //because we want to add from beginning of array i used this variable
            }
       break;
       }
      // add to first array
       else{
           arr1[i] = arr[i];
       }
}

There are different ways to do this! good luck!

Answer 8

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 9

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"]