can someone explain this function

Question

Could someone explain to me how this function works?

var randomize = function(length){
  var text = "";
  var possible = "123abc";

  for (var i = 0 ; i < length; i++)
    text += possible.charAt(Math.floor(Math.random()*possible.length))

  return text;
}

console.log(randomize(6));

I'm trying to understand it but some lines don't make sense.

Answer 1

possible - list of characters to choose from

Math.random() returns a float number between 0 (inclusive) and 1 (exclusive)

Math.random()*possible.length makes it a float number between 0 and possible.length

Math.floor(Math.random()*possible.length) makes it an integer between 0 (inclusive) and possible.length (exclusive)

possible.charAt(position_here) takes a character at position position_here from the string possible (0-indexed)

text += something_here is the same as text = text + something_here . Append another string (in this case: character) to already existing value of text.