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

Andy Poulton
Andy Poulton
UX Design Techdegree Student 6,541 Points

Reference Error on For In Loop Code Challenge

So I keep getting this error even though the code works outside of treehouse.

Bummer: There was an error with your code: ReferenceError: Strict mode forbids implicit creation of global property 'prop'

I'm probably missing something small, but this is driving me nuts.

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

for (prop in shanghai){
  console.log(prop);

};
index.html
<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
  <title>JavaScript Objects</title>
</head>
<body>
<script src="script.js"></script>
</body>
</html>

1 Answer

Sylvester Hofstra
Sylvester Hofstra
12,020 Points

You forgot to declare the variable within the 'for... in'-loop:

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

for (const prop in shanghai){
  console.log(prop);
};