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JavaScript JavaScript Array Iteration Methods Array Manipulation Practice filter()

Samantha McElhinney
Samantha McElhinney
1,931 Points

I'm not sure why I'm getting the error identifier already defined when I'm reassigning the variable with const

const century20 = years.filter(number => number <= 2000);

const years = [1989, 2015, 2000, 1999, 2013, 1973, 2012];
let century20;

// century20 should be: [1989, 2000, 1999, 1973]
// Write your code below
const century20 = years.filter(number => number <= 2000);

1 Answer

I don't think you can change between let and const within the same scope of a program. century20 was initialized (with "no value", which I believe evaluates to null by default) above your code. You no longer need to use the let or const keywords on that variable name, or identifier, within this program scope.

It may be clearer to you if it was declared with an initial value, such as let century20 = [] to help mentally track that the variable already exists.