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3imed-jaberi/nan-result-for-array-mapped-by-parseInt-solution.js

Created November 29, 2021 23:11
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Why ['1', '7', '11'].map(parseInt) returns [1, NaN, 3] in Javascript.
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nan-result-for-array-mapped-by-parseInt-solution.js
/**
* ['1', '7', '11'].map(parseInt) doesn’t work as intended because map passes
* three arguments into parseInt() on each iteration. The second argument
* index is passed into parseInt as a radix parameter. So, each string in the array
* is parsed using a different radix. '7' is parsed as radix 1, which is NaN,
* '11' is parsed as radix 2, which is 3. '1' is parsed as the default radix 10,
* because its index 0 is falsy.
*
* And so, the following code will work as intended;
*/
['1', '7', '11'].map(numberStr => parseInt(numberStr))
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