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JavaScript

virus200
virus200
6,583 Points
Posted by virus200
virus200
6,583 Points

The order of JavaScript variables and functions

Generally programming code executes top to bottom unless conditionals or something come into play to change the execution order. It is said it is best practice to place variables at the top of code in JavaScript which means there may be a variable declared that calls a function that is declared later in the code. How does that variable call a function that hasn't been declared yet like from the code snippet from a lesson below?

var randomNumber = getRandomNumber(10);
var guess;
var guessCount = 0;

function getRandomNumber( upper ) {
  var num = Math.floor(Math.random() * upper) + 1; 
  return num;
}

1 Answer

Adam N
Adam N
70,280 Points
Adam N
Adam N
70,280 Points

function declarations are hoisted. Function expressions aren't. So, if you didn't want this to happen with your code you would rewrite the getRandomNumber function like this

var getRandomNumber = function( upper ) {
  var num = Math.floor(Math.random() * upper) + 1; 
  return num;
}

Get more info here

Let me know if this helps