xo-utils v2.3.0
Helper utils for working with functions, arrays and objects in JavaScript. Full documentation at http://bjdixon.github.io/xo/
Introduction
xo is a library I use to work with functions, arrays and objects in JavaScript.
##Source code The source is available at: http://github.com/bjdixon/xo.
##Installation
####Browser
Download and add to your html pages.
<script type="text/javascript" src="xo.min.js"></script>
####Node
Using npm:
npm install xo-utils
var xo = require('xo-utils');
var curry = require('xo-utils').curry;
##Contains
- curry
- compose
- pipe
- filter
- findIndex
- findKey
- find
- flatten
- compact
- memoize
- isArray
- isFunction
- isObject
- isString
- isNumber
- isBoolean
- maybe
- partial
##Usage
####curry
Takes a function and zero or more arguments to that function. Returns a function that can be invoked with remaining arguments at a later time.
const add = (a, b) => a + b;
const addTen = xo.curry(add, 10);
addTen(32); // => 42
####compose
Takes functions and returns a function. The returned function when invoked will invoke each function that was supplied as an argument to compose (in reverse order) passing the the return value of each as an argument to the next function.
const increment = (a) => a + 1;
const square = (a) => a * a;
const squarePlusOne = xo.compose(increment, square);
squarePlusOne(3); // => 10
####pipe
Takes functions and returns a function. The returned function when invoked will invoke each function that was supplied as an argument to pipe (in the order supplied) passing the the return value of each as an argument to the next function.
const increment = (a) => a + 1;
const square = (a) => a * a;
const plusOneSquare = xo.pipe(increment, square);
plusOneSquare(3); // => 16
####filter
Takes an array and a predicate. Returns an array with only those terms that pass the predicate.
const compare = (id, obj) => id === obj.id;
const objArr = [
{ name: 'a', id: '001' },
{ name: 'b', id: '003' },
{ name: 'c', id: '003' },
{ name: 'd', id: '004' }
];
xo.filter(objArr, xo.curry(compare, '003')); // => [{ name: 'b', id: '003'},{name: 'c', id: '003'}]
####findIndex
Takes an array and a predicate. Returns the index of the first term that passes the predicate.
const compare = (id, obj) => id === obj.id;
const objArr = [
{ name: 'a', id: '001' },
{ name: 'b', id: '002' },
{ name: 'c', id: '003' },
{ name: 'd', id: '004' }
];
xo.findIndex(objArr, xo.curry(compare, '003')); // => 2
####findKey
Takes an object and a predicate. Returns the key of the first term that passes the predicate.
const compare = (id, obj) => id === obj.id;
const obj = {
hello: { name: 'a', id: '001' },
goodbye: { name: 'b', id: '002' },
yes: { name: 'c', id: '003' },
no: { name: 'd', id: '004' }
} ;
xo.findKey(obj, xo.curry(compare, '003')); // => 'yes'
####find
Takes an object or an array and a predicate. Returns the value of the first term that passes the predicate.
const compare = (id, obj) => id === obj.id;
const obj = {
hello: { name: 'a', id: '001' },
goodbye: { name: 'b', id: '002' },
yes: { name: 'c', id: '003' },
no: { name: 'd', id: '004' }
};
const objArr = [
{ name: 'a', id: '001' },
{ name: 'b', id: '002' },
{ name: 'c', id: '003' },
{ name: 'd', id: '004' }
];
xo.find(obj, xo.curry(compare, '003')); // => { name: 'c', id: '003' }
xo.find(objArr, xo.curry(compare, '003')); // => { name: 'c', id: '003' }
####flatten
Takes an n-dimensional nested array. Returns a flattened 1-dimension array.
const test = [0, 1, [2, 3], [4, [5, 6]], 7, [8, [9]]];
xo.flatten(test); // => [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
####compact
Takes an array. Returns an array with all falsy values removed.
const test = [1, , false, 2, 3, false];
xo.compact(test); // => [1, 2, 3]
####memoize
Takes a function and returns a functions. Invoking the returned function will return cached results if the same arguments have been provided during previous invocations.
const upper = (str) => str.toUpperCase();
const memoUpper = xo.memoize(upper);
memoUpper('foo'); // => "FOO"
memoUpper('foo'); // => "FOO" (cached version)
####isArray
Type check for Array.
xo.isArray([1, 2, 3]); // => true
xo.isArray(true); // => false
####isFunction
Type check for Function.
xo.isFunction(function(){ return true; }); // => true
xo.isFunction(true); // => false
####isObject
Type check for Object.
xo.isObject({ a: true }); // => true
xo.isObject(true); // => false
####isString
Type check for String.
xo.isString('true'); // => true
xo.isString(true); // => false
####isNumber
Type check for Number.
xo.isNumber(42); // => true
xo.isNumber('true'); // => false
####isBoolean
Type check for Boolean.
xo.isBoolean(true); // => true
xo.isBoolean('true'); // => false
####maybe
Takes a function and returns a function. The returned function will not be invoked if supplied with null or undefined arguments.
const sum = (a, b) => a + b;
const maybeSum = xo.maybe(sum);
maybeSum(2, 3); // => 5
maybeSum(null, 3); // doesn't invoke sum
####partial
Takes a function and zero or more arguments to that function. Returns a function that can be invoked with remaining arguments at a later time.
const add = (a, b) => a + b;
const addTen = xo.partial(add, 10);
addTen(32); // => 42
####map
Takes an array and a function. Returns an array that is the result of applying the function to each term of the original array.
const arr = [1, 2, 3, 4];
const square = (a) => a * a;
const out = xo.map(square, arr); // => [1, 4, 9, 16];
####reduce
Takes an array, an initial value and a function. Returns a single value that is the result of applying the function to each term of the array and an accumulator.
const arr = [1, 2, 3, 4];
const sum = (a, b) => a + b;
const out = xo.reduce(sum, 0, arr); // => 10;