type-reverse
v2.0.2
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🦄 Lightweight reverse utility around strings, arrays, numbers and more.
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type-reverse
🦄 Lightweight reverse utility around strings, arrays, numbers and more.
Install
$ npm install --save type-reverse
Usage
const reverse = require('type-reverse')
or...
import reverse from 'type-reverse'
API
reverse( input[, options][, callback] )
Params
input
{String|Number|Array|Set}options
{?Object}callback
{?Function}returns
{*}
reverse('pizza')
//=> azzip
Works with numbers too.
reverse(1234)
//=> 4321
Reversing arrays...
When JavaScript's Array#reverse method is used, the original array is mutated, as in, the indexes of the elements are changed. On the other hand, this utility adopts the non-destructive array reversal method, which means the reverse()
function doesn't mutate the array; it just returns the reversed array and still maintains the indexes of the elements in the original array.
native reverse...
const arr = [1, 2, 3]
arr.reverse() //=> [3, 2, 1]
Oops, we lost the indexes of elements in the initial array...
console.log(arr) //=> [3, 2, 1]
vs...
🦄 to the rescue...
const arr = [1, 2, 3]
reverse(arr) //=> [3, 2, 1]
Yay! arr
is not mutated. The indexes of its elements are still maintained...
console.log(arr) //=> [1, 2, 3]
Sets
If you've been wondering how to reverse Sets in JavaScript, here's it! The core reverse
function can take in a Set
as the input and then return the reversed Set
...
const set = new Set([5, 4, 3, 4, 5])
reverse(set) //=> Set { 3, 4, 5 }
options
options
is the second parameter to the function call and it is an object with two available properties. It can also take in a falsy value which would implicity get converted to an empty object.
invert: {String}
This property defaults to index
and applies to strings and numbers only.
reverse(/*...*/, {
invert: '[index|word|sign]'
})
index
- interchanges the indexes of characters in the input...reverse(12345, { invert: 'index' }) //=> 54321 reverse('of... unicorns', { invert: 'index' }) //=> snrocinu ...fo
sign
- inverts the sign in a number...reverse(1234, { invert: 'sign' }) //=> -1234
word
- swaps the location of words in a string...reverse('of... unicorns', { invert: 'word' }) //=> unicorns of...
preserveZeros: {Boolean}
This property defaults to true
. It specifies whether to enforce preceding zeros in the result of a number that contains trailing zeros. See #3 for more info. Note that the result gets converted to a string. Disabling it would look like this...
reverse(240, { preserveZeros: false }) //=> 42
callback: {Function}
The callback takes in a function with two optional parameters that represent input
and result
respectively.
input
- the initial input that was passed into the functionresult
- the output from reversing the input
const text = 'dog'
reverse(text, null, function(intitial, result) {
return intitial + ' was changed to ' + result
}) //=> dog was changed to god
Limits
Did you just try to reverse a reaally huge number? Unfortunately, this utility doesn't support very large numbers. Trying to do so with this utility would throw a TypeError.
Author
Olaolu Olawuyi
License
MIT © Olaolu Olawuyi