Javascript array map method callback parameters

Question

Javascript describes the syntax of a map method as:

arr.map (callback [, thisArg])

Parameters

• callback is a function that creates an element of a new array using three arguments:
• currentValue - the current element is processed in the array.
• index - the index of the current element being processed in the array. Array
• An array map is provided.
• thisArg is the value to use when executing the callback.

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/map

I can write a JS function that will capitalize the first letter of each word in an array of strings as follows:

capyyIt(['john', 'nelson mandela', 'james booth'])     // returns ['John', 'Nelson mandela', 'James booth']

function capyyIt(names) {
  return names.map(function capIt(curr) { return curr[0].toUpperCase() + curr.slice(1).toLowerCase(); });
}

• capIt 4 ( )? , 4 , , , .

• capIt , - - :

  function capyyIt(names) {
      return names.map(capIt);
  }
  function capIt(curr,index,arr) {
      return curr[0].toUpperCase() + curr.slice(1).toLowerCase();
  }
  

Answer 1

, , , :

function capyyIt(names) {
  names.map(function(value, index, collection){
     capIt(val);
  })
}   

function capIt(name) {
  return name.toUpperCase() + curr.slice(1).toLowerCase();
}

map , , , . , - , .