如何知道哪个 arguments 在 javascript 的匿名函数中作为参数传递

Question

I am completely new to Javascript and I'm wondering how the anonymous functions know which arguments are being passed as parameters. Let me explain my doubt with the help of code:

camelize = function camelize(str) {
      return str.replace(/\W+(.)/g, function(match, chr)
       {
            return chr.toUpperCase();
        });
    }

console.log(camelize("JavaScript Exercises"));
console.log(camelize("JavaScript exercises"));
console.log(camelize("JavaScriptExercises"));

This code is supposed to return a camelcase version of the input string. I understand that the regex finds non-word characters globally. But how does the function inside know what are "match" and "chr"?

Answer 1

The replace function accepts a function as its second parameter which it then calls, passing the results of the regex as the parameters of your function.

Here's an example of how one could implement a similar pattern

 function foo(str, func) { for(let i in str) { //for every character func(i, str[i]); // call func with the index and character } } foo("hello world", function(index, char) { console.log(index, char); });