1num.toString();

1var num = 15;
2var n = num.toString(); /* now */ "15"

1obj.toString()

1toString . 
2For user-defined Function objects, 
3  the toString method returns a string containing the source text segment 
4  which was used to define the function. JavaScript calls the toString method
5  automatically when a Function is to be represented as a text value, 
6    e.g. when a function is concatenated with a string.
7

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

1const num = 15;
2const n = num.toString(); /* now */ "15"