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exist-utils
Advanced tools
This package is a collection of util functions that emulate CoffeeScript existence operator. While waiting that some of them are integrated in the next version of JavaScript, you can use this package while porting from CoffeeScript, etc.
npm install exist-utils
You can then ExistUtils = require('exist-utils')
or import * as ExistUtils from 'exist-utils'
.
Use the minified UMD build in the dist
folder: here.
It exports a global window.ExistUtils
when imported as a <script>
tag.
Each function as a full name (i.e. exists
) and a shorthand (i.e. ex
), both are specified in the title of their description.
You can check the equivalence with CoffeeScript operators in the following section.
exists
(ex
)Example:
if (!exists(arg)) {
error('missing arg');
}
This is the equivalent to CoffeeScript val?
, it checks if a value "exists" (is neither null
nor undefined
).
existsChained
(exc
)Example:
if (!existsChained(arg, 'callback')) {
error('no callback specified');
}
This is the equivalent to CoffeeScript obj?.prop?
, it checks if a whole chain "exists".
existsChainedValue
(excv
)Example:
const callback = existsChainedValue(arg, 'callback');
if (!exists(callback)) {
error('no callback specified');
return;
}
callback();
This is the equivalent to CoffeeScript obj?.prop
, it checks if a whole chain "exists" and returns the final value.
elvis
(el
)Example:
val = elvis(arg, 42);
This is the equivalent to CoffeeScript val ? default
and a safer version to val || default
.
It returns the second value if the first one doesn't "exist".
callsIfExist
(fnex
)Example:
callsIfExist(func, 1, 2);
This is the equivalent to CoffeeScript func?(1, 2)
, it checks the existence of the function and calls it with the provided arguments.
callsIfExistObj
(fnexo
)Example:
callsIfExistObj(obj, 'func', 1, 2);
This is the equivalent to CoffeeScript obj?.func?(1, 2)
, it checks the existence of the function and calls it with the provided arguments while providing the right value for this
.
CoffeeScript | exist-utils | exist-utils shorthand |
---|---|---|
val? | exists(val) | ex(val) |
obj?.prop? | existsChained(obj, 'prop') | exc(obj, 'prop') |
obj?.prop | existsChainedValue(obj, 'prop') | excv(obj, 'prop') |
val = arg ? 3 | val = elvis(arg, 3) | val = el(arg, 3) |
func?(a, b) | callsIfExist(func, a, b) | fnex(func, a, b) |
obj.func?(a, b) | callsIfExistObj(obj, func, a, b) | fnexo(obj, func, a, b) |
MIT, Copyright (c) 2017-2020 Louis Brunner
FAQs
Utility functions that emulate CoffeeScript existence operator
The npm package exist-utils receives a total of 7 weekly downloads. As such, exist-utils popularity was classified as not popular.
We found that exist-utils demonstrated a not healthy version release cadence and project activity because the last version was released a year ago. It has 1 open source maintainer collaborating on the project.
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