How to Filter for True Values in an Array in JavaScript
Ferenc Almasi •
2021 April 26 • 
2 min read
Probably one of the simplest and cleanest ways to get rid of falsy values in JavaScript is by utilizing the built-in filter array function the following way:
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// Filter out falsy values by simply passing Boolean to Array.prototype.filter
[
1, 2, 3, 0,
undefined,
null,
false,
true,
'',
'I’m truthy 🙂'
].filter(Boolean);
// Results in the following array:
[1, 2, 3, true, 'I’m truthy 🙂'];The only problem is that this won't work for nested arrays. To get around this, you can use the below function which uses recursion to filter out falsy values from a nested array:
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const filterFalsy = array => array.filter(Boolean)
.map(item => Array.isArray(item) ? filterFalsy(item) : item);
const array = [
1, 2, 3, 0,
undefined,
null,
false,
true,
[0, 1, 2, '', [false, true]],
'',
'I’m truthy 🙂'
];
filterFalsy(array); // This will return the following array:
[1, 2, 3, true, [1, 2, [true]], "I’m truthy 🙂"]
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