Sum of numbers in a string

SumNumbers.js

/**
 * Created by Albert Hoan on 2/27/2017.
 */

//input: str = '123abc4xyz' => output: sum=123+4=127
//input: str= '1abc34' => output= 35;


function decodeNumber(str) {

	var arr = [];
	var res = '';
	var len = str.length - 1;

	for (var i = 0; i <= len; i++) {

		if (!isNaN(str.charAt(i))) {
			res = res + str.charAt(i);
			if (i == len) {
				arr.push(parseInt(res));
			}
		} else {
			if (i <= len && (res.length !== 0)) {
				arr.push(parseInt(res));
				res = '';
			}
		}
	}
	return arr.length !== 0 ? arr.reduce(function(a, b) {
			return a + b;
		}) : 0;
}


var str = '1sdsd343a';
var str2 = '1abc123';
var str3 = 'abc';
console.log(decodeNumber(str));
console.log(decodeNumber(str2));
console.log(decodeNumber(str3));