- 1: 4 - 2: NaN - 3: SyntaxError - 4: -1

##### Answer: 4 The indexOf uses strict equality operator(===) internally and NaN === NaN evaluates to false. Since indexOf won't be able to find NaN inside an array, it returns -1 always. But you can use Array.prototype.findIndex method to find out the index of NaN in an array or You can use Array.prototype.includes to check if NaN is present in an array or not.

JS Coding Questions

#22🎯 Exercise💻 Code

JavaScript Coding Exercise 22

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javascript

1let numbers = [1, 2, 3, 4, NaN];
2
3console.log(numbers.indexOf(NaN));

Choose the correct output:

NaN

SyntaxError

-1

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