Javascript Split method

Question

var string = abc123;
string.split(*POSITION=3)???

Is there a way to split this string into an array of strings that is [abc,123]? Is the split method the right thing to use?

• nickd: split() needs a delimiter to work.

Answer 1

I would say the split method is not the right thing to use here, as its purpose is to segment a string based on a certain character.

You could certainly write your own function, of course:

function partition(str, index) {
 return [str.substring(0, index), str.substring(index)];
}
// results in ["123", "abc"]
var parts = partition("123abc", 3);

If you wanted to write "123abc".partition(3) instead, you could make that possible by extending String.prototype:

String.prototype.partition = function(index) {
 return [this.substring(0, index), this.substring(index)];
};

Personally, though, I'd recommend avoiding that sort of tomfoolery (search the web for "extending built-in objects in JavaScript" if you want to read what others have to say on the topic).

• rob: Just curious (because I see this time to time), if you don't recommend doing it by extending the prototype, why not do it in the way you do recommend? e.g.: function partionString(str, index) {...
• Esailija: I highly doubt this is what the OP wants... "hello friend".partition(3) ["hel", "lo friend"] doesn't split *POSITION=3 at all for me. Then again, *POSITION=3 is very open to interpretation :D Just putting it out there.
• Dan Tao: @rob: Totally fair point; I've updated my answer accordingly.
• Dan Tao: @Esailija: It certainly is open to interpretation... I see, your interpretation was that he wants to split the string up into an arbitrary number of segments of equal length? My answer reflects what I think he wants: to cut a string in two parts around a specified position. But you're right; it's very possible I've misconstrued the OP's intent.
• Esailija: @DanTao, I mean like if you have a string "FFFFFF" and then do *POSITION=2 split, you will end up with ["FF", "FF", "FF"] (Split every 2 characters), which is the kind of functionality php str_split does. But looks like he wasn't looking for that after all :P

Answer 2

Maybe use a simple RegExp match?

var arr = "abc123".match(/^([a-z]+)(\d+)$/i);
arr.shift();
console.log(arr);

Answer 3

var arr = "this is a test".match(/.{1,3}/g);

Answer 4

No but it is trivial to implement that:

function splitn( str, n ){
var r = [], offset = 0, l = str.length;
 while( offset < l ) {
 r.push( str.substr( offset, n ) );
 offset += n;
 }
return r;
}

Then:

var string = "abc123";
console.log( splitn( string, 3 ) );
//["abc", "123"]

Assuming you want similar functionality to str_split