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num == null judgment is not rigorous #5

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num == null judgment is not rigorous #5

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5ce0c26
add: rigorous undefined judgment
jweboy Apr 9, 2018
0b68387
Merge branch 'fix-bug'
jweboy Apr 9, 2018
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2 changes: 1 addition & 1 deletion index.js
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Original file line number Diff line number Diff line change
Expand Up @@ -18,7 +18,7 @@ module.exports = function arrayFirst(arr, num) {
}

var first = slice(arr, 0, isNumber(num) ? +num : 1);
if (+num === 1 || num == null) {
if (+num === 1 || num === undefined) {
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It's more rigorous than num === undefined.

var undefined = 'foo';
var val;
console.log(val === undefined) // false
console.log(val == null) // true

This is because undefined can be a defined value, but num == null checks both typeof num === 'undefined' and num === null.

return first[0];
}
return first;
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