1// JavaScript
2(new Blob(['20€'])).size;		// 5
3
4// Node js
5Buffer.from('20€').length;	// 5

1      getStringMemorySize = function( _string ) {
2        "use strict";
3
4        var codePoint
5            , accum = 0
6        ;
7
8        for( var stringIndex = 0, endOfString = _string.length; stringIndex < endOfString; stringIndex++ ) {
9            codePoint = _string.charCodeAt( stringIndex );
10
11            if( codePoint < 0x100 ) {
12                accum += 1;
13                continue;
14            }
15
16            if( codePoint < 0x10000 ) {
17                accum += 2;
18                continue;
19            }
20
21            if( codePoint < 0x1000000 ) {
22                accum += 3;
23            } else {
24                accum += 4;
25            }
26        }
27
28        return accum * 2;
29    }
30