Posted almost 3 years ago. Visible to the public. Repeats.

LoDash: isBlank and isPresent mixins

When you need to check a value for presence, don't rely on JavaScript since it considers 0 or "0" false. Also don't rely on LoDash's _.isEmpty:

if ('0') { ... } // false if (0) { ... } // false
if (!_.isEmpty('0')) { ... } // true (= good) if (!_.isEmpty(0)) { ... } // false (= not good)

This is because isEmpty it is only meant for objects with a length.

While the name implies that it's meant only for collections, you probably still want something like isBlank or isPresent that return true/false for objects humans would normally consider blank or present.

Here is some CoffeeScript that provides _.isBlank and _.isPresent via LoDash/Underscore.js mixins:

_.mixin isBlank: (object) -> switch typeof object when 'boolean' then false when 'function' then false when 'number' then isNaN(object) else _.isEmpty(object) isPresent: (object) -> !_.isBlank(object) , chain: false

Use them like this:

_.isBlank(0) // false _.isBlank(23) // false _.isBlank('') // true
_.isPresent(null) // false _.isPresent(NaN) // false

The chain: false option above also allows to use them as terminal methods:

_(23).isBlank() // false _(23).isPresent() // true

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Author of this card:

Arne Hartherz
Last edit:
3 months ago
by Henning Koch
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Posted by Arne Hartherz to makandropedia