Fast way to concatenate strings in nodeJS/JavaScript [duplicate]

Question

I understand that doing something like

var a = "hello"; a += " world"; 

It is relatively very slow, as the browser does that in O(n) . Is there a faster way of doing so without installing new libraries?

Answer 1

The question is already answered, however when I first saw it I thought of NodeJS Buffer. But it is way slower than the +, so it is likely that nothing can be faster than + in string concetanation.

Tested with the following code:

function a(){     var s = "hello";     var p = "world";     s = s + p;     return s; }  function b(){     var s = new Buffer("hello");     var p = new Buffer("world");     s = Buffer.concat([s,p]);     return s; }  var times = 100000;  var t1 = new Date(); for( var i = 0; i < times; i++){     a(); }  var t2 = new Date(); console.log("Normal took: " + (t2-t1) + " ms."); for ( var i = 0; i < times; i++){     b(); }  var t3 = new Date();  console.log("Buffer took: " + (t3-t2) + " ms."); 

Output:

Normal took: 4 ms. Buffer took: 458 ms. 

Answer 2

There is not really any other way in JavaScript to concatenate strings.
You could theoretically use .concat(), but that's way slower than just +

Libraries are more often than not slower than native JavaScript, especially on basic operations like string concatenation, or numerical operations.

Simply put: + is the fastest.