Question

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JavaScript string concatenation
does javascript have a built in stringbuilder class?

As it’s known when we do str = str + "123" a new string is created. If we have a large number of concatenations it can be rather expensive. Is there a simple way to implement a StringBuilder in JavaScript?

Answer 1

You can push the parts into an array, and then join it:

var builder = []
builder.push( "some", "123" );
builder.push( "content" );
var str = builder.join("");

This SO question explains it in detail, see also this class