# FAQ: Code Challenges: JavaScript Fundamentals - calculateWeight()

This community-built FAQ covers the “calculateWeight()” exercise from the lesson “Code Challenges: JavaScript Fundamentals”.

Paths and Courses
This exercise can be found in the following Codecademy content:

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3 posts were split to a new topic: Difference between using `=` and `===`?

5 posts were merged into an existing topic: Difference between using `=` and `===`?

2 posts were split to a new topic: What is wrong with my code?

2 posts were split to a new topic: Do I need to use break or return?

4 posts were split to a new topic: Returning a string instead of a number

3 posts were split to a new topic: String not exact?

2 posts were merged into an existing topic: String not exact?

2 posts were split to a new topic: Should I create an error to check for a number and planet name?

7 posts were merged into an existing topic: String not exact?

5 posts were merged into an existing topic: Do I need to use break or return?

Hi there !

I tried to use an if / else if / else statement for this exercise. When I try the example given in the exercise, ie. console.log(calculateWeight(100, ‘Jupiter’)); , I get 37.8 as if I entered ‘Mercury’ as the second argument.
I can’t seem to find out the reason, can you help me please ? Here’s my code :

``````const calculateWeight = (earthWeight, planet) => {
if (planet = 'Mercury') {
return earthWeight * 0.378;
} else if (planet = 'Venus') {
return earthWeight * 0.907;
} else if (planet = 'Mars') {
return earthWeight * 0.377;
} else if (planet = 'Jupiter') {
return earthWeight * 2.36;
} else if (planet = 'Saturn') {
return earthWeight * 0.916;
} else {
return 'Invalid Planet Entry. Try: Mercury, Venus, Mars, Jupiter, or Saturn.';
};
};
``````

That is an assignment operator being used to check for identity. The correct operator is `===`.

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