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JavaScript JavaScript Loops, Arrays and Objects Tracking Data Using Objects Accessing All of the Properties in an Object

derekverrilli
derekverrilli
8,841 Points
Posted by derekverrilli
derekverrilli
8,841 Points

Why do we need to use the var keyword?

I'm curious why not using the 'var' keyword causes an error when in the video, Dave doesn't use it?

script.js 
var shanghai = {
  population: 14.35e6,
  longitude: '31.2000 N',
  latitude: '121.5000 E',
  country: 'CHN'
};

for (var keys in shanghai) {
  console.log(keys);
}
index.html 
<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
  <title>JavaScript Objects</title>
</head>
<body>
<script src="script.js"></script>
</body>
</html>

2 Answers

Marcus Parsons
Marcus Parsons
15,718 Points

Hey Derek,

I'm sure this was just a mistake in the video. In the first part of the video, he uses the var keyword, but he does not in the Workspaces part. I see where you might get confused.

It is a very good practice to use the var keyword when initializing variables for loops so that the variable created doesn't accidentally get hoisted into the global scope. But, I'll tag Dave McFarland so that he can give his answer! :)

derekverrilli
derekverrilli
8,841 Points
derekverrilli
derekverrilli
8,841 Points

Definitely makes sense and I figured as much. Thanks for the reply :)

Marcus Parsons
Marcus Parsons
15,718 Points

You're very welcome =]