change no to string in js

1var num = 15;
2var n = num.toString();

1
2var myNumber=120;
3var myString = myNumber.toString(); //converts number to string "120"

1var number = 1212
2var numberString = number.toString();//converts my number that is '1212' to a string

1const toNumber = str => +str;
2
3// Example
4toNumber('42');     // 42