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

Andy Poulton
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Andy Poulton
UX Design Techdegree Student 6,541 Points
Posted by Andy Poulton
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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
12,022 Points
Sylvester Hofstra
Sylvester Hofstra
12,022 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);
};