JavaScript adding a string to a number

Question

I was reading the re-introduction to JavaScript on MDN and in the section Numbers it said that you can convert a string to a number simply by adding a plus operator

Answer 1

The answer can be found in Ecma262.pdf section 11.6.1:

If Type(lprim) is String or Type(rprim) is String, then a. Return the String that is the result of concatenating ToString( lprim) followed by ToString(rprim).

So that will resolve all operations according to precedence, so that as soon the string is found any number, the number is converted to string.

4 + 3 + "5"
"75"
4 + 3 + "5" + 3
"753"

To read the whole standard, go here.