[removed] how to pass found string.replace value to function?

Question

When I have something like this:

var str = \"0123\";
var i = 0;
str.replace(/(\\d)/g,function(s){i++;return s;}(\'$1\'));
alert(i);

Why doe

Answer 1

When you use string.replace(rx,function) then the function is called with the following arguments:

• The matched substring
• Match1,2,3,4 etc (parenthesized substring matches)
• The offset of the substring
• The full string

You can read all about it here

In your case $1 equals Match1, so you can rewrite your code to the following and it should work as you desire:

var str = "0123";
var i = 0;
str.replace(/(\d)/g,function(s,m1){i++;return m1;});
alert(i);

Answer 2

You are calling the function, which increments i once, and then returns the string '$1'.

To pass the value to a function, you can do:

str.replace(/\d/g, function (s) { /* do something with s */ });

However, it looks like you don't actually want to replace anything... you just want a count of the number of digits. If so, then replace is the wrong tool. Try:

i = str.match(/\d/g).length;

Answer 3

The expression

function(s){i++;return s;}('$1')

Creates the function and immediately evaluates it, passing $1 as an argument. The str.replace method already receives a string as its second argument, not a function. I believe you want this:

str.replace(/(\d)/g,function(s){i++;return s;});