midash

midash API

Object

get

Get the attribute of object deeply.

const object = { a: [{ b: 3 }] }
 
// => 3
_.get(object, 'a[0].b')
 
// => 3
_.get(object, ['a', '0', 'b'])
 
// => 'default'
_.get(object, 'a.b.c', 'default')

omit

Ingore attributes of object and return new object.

WARNING

_.omit(object, 'a', 'b') can't work well in midash. use _.omit(object, ['a', 'b']) instead.

const object = {
  a: 3,
  b: 4,
  c: 5
}

//=> { c: 5 }
_.omit(object, ['a', 'b'])

omitBy

Ingore attributes of object by function and return new object.

const object = {
  a: 3,
  b: 4,
  c: 5
}

// omit by value
//=> { b:4, c: 5 }
_.omitBy(object, value => value === 3)

// omit by key
//=> { b:4, c: 5 }
_.omitBy(object, (value, key) => key === 'a')

pick

Pick attributes of object by function and return new object.

WARNING

_.pick(object, 'a', 'b') can't work well in midash, use _.pick(object, ['a', 'b']) instead.

const object = {
  a: 3,
  b: 4,
  c: undefined
}

//=> { a: 3, b: 4 }
_.pick(object, ['a', 'b'])

//=> {}
_.pick(object, ['z'])

//=> { c: undefined }
_.pick(object, ['c'])

pickBy

通过函数选择 object 的某些属性，并返回新的 object。

const object = {
  a: 3,
  b: 4,
}

//=> { a: 3 }
_.pickBy(object, value => value === 3)

//=> { a: 3 }
_.pickBy(object, (value, key) => key === 'a')

defaults

//=> { mode: 'development', sourcemap: true, devtool: true }
_.defaults({
  mode: 'development',
  sourcemap: true
}, {
  mode: 'production',
  devtool: true
})

clone

const o = { a: { aa: 3 }, b: 4 }

//=> true
_.clone(o).a === o.a

cloneDeep

const o = { a: { aa: 3 }, b: 4 }

//=> false
_.cloneDeep(o).a === o.a

merge

Merges one or more objects into first object recursively and return new object.

//=> { a: 4, b: 2 }
merge({ a: 1 }, { b: 2 }, { a: 3 }, { a: 4 })

assign

Assigns own enumerable string keyed properties of source objects to the destination object. Source objects are applied from left to right. Subsequent sources overwrite property assignments of previous sources.

// => { a: 1, b: 3, c: 5, d: 6 }
_.assign({ a: 1, b: 2 }, { b: 3, c: 4 }, { c: 5, d: 6 })

mapKeys

//=> { a3: 3, b4: 4 }
mapKeys({ a: 3, b: 4 }, (v, k) => `${k}${v}`)

mapValues

//=> { a: 4, b: 5 }
mapValues({ a: 3, b: 4 }, (v) => v + 1)

Array

chunk

Get an array of elements split into chunk by size.

//=> [[0, 1, 2], [3, 4, 5]]
_.chunk([0, 1, 2, 3, 4, 5], 3)

//=> [[0], [1], [2]]
_.chunk([0, 1, 2])

//=> [['a', 'b', 'c'], ['d', 'e', 'f'], ['g', 'h', 'i']]
_.chunk('abcdefghi', 3)

sample

Get a random element from an array.

// get a random element from [0, 3, 6, 10]
_.sample([0, 3, 6, 10])

//=> undefined
_.sample([])

sampleSize

Get n random element from an array.

//=> Maybe [1, 2]
_.sampleSize([1, 2, 3], 2)
 
//=> [1, 2, 3]
_.sampleSize([1, 2, 3], 4)

difference/differenceBy

TIP

在 midash 中，differenceBy 是 difference 的别名。

//=> [2, 4]
difference([1, 2, 3, 4], [1, 3, 5])

//=> [{ a: 4 }]
differenceBy([{ a: 3 }, { a: 4 }], [{ a: 3 }], x => x.a)

shuffle

uniq

keyBy

const list = [
  { id: 1, name: 'hello' },
  { id: 2, name: 'world' },
]

//=> { '1': { id: 1, name: 'hello' }, '2', { id: 2, name: 'world' } }
_.keyBy(list, x => id)

groupBy

//=> { '3': ['one', 'two'], '5': ['three'] }
_.groupBy(['one', 'two', 'three'], x => x.length)

get

zip

Creates an array of grouped elements, the first of which contains the first elements of the given arrays, the second of which contains the second elements of the given arrays, and so on.

// => [[1, 'a', true],[2, 'b', false],[3, 'c', undefined]];
_.zip([1, 2, 3], ['a', 'b', 'c'], [true, false]);

// => [[undefined, 1], [undefined, 2], [undefined, 3]];
_.zip([],[1, 2, 3])

// => [[1, 'a', undefined], [2, 'b', undefined],[undefined, 'c', undefined]];
_.zip([1, 2], ['a', 'b', 'c'], [])

unzip

This method is like _.zip except that it accepts an array of grouped elements and creates an array regrouping the elements to their pre-zip configuration.

// => [[1, 2, 3], ['a', 'b', 'c'], [true, false, true]]
_.unzip([[1, 'a', true], [2, 'b', false], [3, 'c', true]])

// => []
_.unzip([])

// => [[1, 2, 4], ['a', 'b', 'c'], [undefined, 3, undefined]]
_.unzip([[1, 'a'], [2, 'b', 3], [4, 'c']])

String

camelCase

snakeCase

kebabCase

String

Number

random

Get the random integer.

// an integer between 10 and 20, includes 10 and 20
_.random(10, 20)

// an integer between 0 and 20
_.random(20)

// an integer between 0 and 1
_.random()

Lang

castArray

Casts value as an array if it's not one.

_.castArray(1);
// => [1]
 
_.castArray({ 'a': 1 });
// => [{ 'a': 1 }]
 
_.castArray('abc');
// => ['abc']
 
_.castArray(null);
// => [null]
 
_.castArray(undefined);
// => [undefined]
 
_.castArray();
// => []
 
const array = [1, 2, 3];
console.log(_.castArray(array) === array);
// => true

isArray

//=> true
_.isArray([])

isObject

//=> true
_.isObject({})

//=> true
_.isObject([])

//=> true
_.isObject(x => {})

isPlainObject

//=> true
_.isPlainObject({})

//=> true
_.isPlainObject(Object.create(null))

//=> false
_.isPlainObject(new Date())

isPromise

//=> true
_.isPromise(Promise.resolve())

isTypedArray

//=> true
_.isTypedArray(new Uint8Array([1, 2, 3]))

isEqual

Util

compose/flowRight

从右至左执行函数，并将上一个函数的返回值作为下一个函数的参数。

flowRight is an alias to compose.

const double = x => x * 2
const square = x => x * x

//=> 200
_.compose(double, square)(10)
_.flowRight(double, square)(10)

property

Creates a function that returns the value at path of a given object.

const objects = [
  { 'a': { 'b': 2 } },
  { 'a': { 'b': 1 } }
];
// => [2, 1]
_.map(objects, _.property('a.b'));

// => [1, 2]
_.map(_.sortBy(objects, _.property(['a', 'b'])), 'a.b');

once

只会调用一次的函数。

// `initialize` 只能调用 `createApplication` 一次。
const initialize = _.once(createApplication);
initialize();
initialize();

memoize

创建一个会缓存 func 结果的函数。

const object = { 'a': 1, 'b': 2 };
const other = { 'c': 3, 'd': 4 };

// => [1, 2]
const values = memoize(Object.values,);
values(object);

// => [3, 4]
values(other);

object.a = 2;
// => [1, 2]
values(object);

range

Get the range of numbers.

//=> [0, 1, 2, 3]
range(4)

//=> [0, -1, -2, -3]
range(-4)

//=> [1, 2, 3, 4]
range(1, 5)

//=> [5, 4, 3, 2]
range(5, 1)

//=> [0, -1, -2, -3]
range(0, -4, -1)

Math

sum

max

Get the maximum value from an array. If array is empty or falsy, undefined is returned.

In midash，maxBy is an alias to max.

// => 5
_.max([-5, -3, 0, 3, 5])

// => { a: 4 }
_.maxBy([
  { a: 3 },
  { a: 4 }
], x => x.a)

min

Get the minimum value from an array. If array is empty or falsy, undefined is returned.

TIP

In midash，minBy is an alias to min.

// => -5
_.min([-5, -3, 0, 3, 5])

// => { a: 3 }
_.minBy([
  { a: 3 },
  { a: 4 }
], x => x.a)