Lodash 开发速查手册

Lodash 是一个一致性、模块化、高性能的 JavaScript 实用工具库。

CollectionsFindingAccessingSet/getIterationArrayArraysFilteringAccessingSetsIndexesFunctionsCurryingDecorating functionsThrottlingLimitingEtcStringsCapitalizationPaddingTrimEtcObjectsKeys and valuesChainingChain and value

Collections

Finding

_.filter(list, (n) => n % 2)    // → Array
_.find(list, (n) => n % 2)      // → item
_.findLast(list, ...)           // → item

Works for both arrays and objects.

Accessing

// → [ a ] - same as list[0]
_.at([ abcd ], 0) 
// → [ ab ]
_.at([ abcd ], [ 0, 1 ])

Set/get

_.set(object, 'users[0].name', value)
_.get(object, 'users[0].name')
_.get(object, ['users', 0, 'name'])

Iteration

_.forEach(list, (item, i) => ...)
_.forEachRight(list, ...)

_.map(list, ...)

// → true|false (aka _.all)
_.every(users, (u) => u.active)  
// → true|false (aka _.some)
_.any(users, ...)

Array

Arrays

_.chunk([ abcd ], 2)  // → [ [ab], [cd] ]
_.compact(list)

// → [ 'x', 'x', 'x', 'x' ]
_.fill(Array(4), 'x') 
_.flatten
_.flattenDeep

Filtering

_.drop([ abcdef ], 2)// → [   cdef ]
_.dropRight([ abcdef ], 2)// → [ abcd   ]
_.take([ abcdef ], 2) // → [ ab     ]
_.takeRight([ abcdef ], 2)// → [     de ]
_.slice([ abcdef ], 2, 4) // → [   cd   ]

// → [ abcde  ] - dropRight(list, 1)
_.initial([ abcdef ]) 
// → [  bcdef ] - takeRight(list, 1)
_.rest([ abcdef ]) 

// works like filter
_.dropWhile(list, 'active') 
_.dropWhile(list, 'active', true)
_.dropWhile(list, { active: true })
_.dropWhile(list, (n) => ...)
_.dropRightWhile(list, ...)

_.without([ abcde ], b)// → [ acde ]

_.remove(list, (n) => n % 2)

Accessing

_.first([ abcdef ])            // → a
_.last([ abcdef ])             // → f

Sets

_.uniq()
_.difference([ abc ], [ bc ])// → [ a    ]
 // → [  bc  ]
_.intersection([ abc ], [ bcd ])   
// → [ abcd ] (unique)
_.union([ abc ], [ bcd ])           

Array#concat()

Indexes

_.findIndex(list, fn)
_.findLastIndex(list, fn)

_.sortedIndex(list, val)
_.sortedLastIndex(list, val)

_.indexOf(list, val)

Functions

Currying

greet = (greeting, name) =>
`${greeting}, ${name}!`

{: .-setup}

fn = _.partial(fn, 'hi')
fn('joe')    // → 'hi, joe!'

fn = _.partial(fn, 'joe')
fn('yo')     // → 'yo, joe!'

// → function(name)
_.curry(greet)('hi')        
// → function(greet)
_.curryRight(greet)('joe')

Decorating functions

Throttling

_.throttle(fn)
_.debounce(fn)

Limiting

_.before(5, fn)  // only works 5 times
_.after(5, fn)  // works only after 5 times
_.once(fn) // like _.before(fn, 1)

Etc

_.wrap(_.escape, (name) => `hi ${name}`)
// same as doing `name = _.escape(name)`

_.delay(fn, 2000)

_.negate(fn)

_.memoize(fn)
_.memoize(fn, ...)

Strings

Capitalization

_.capitalize('hello world')// → 'Hello world'
_.startCase('hello_world')// → 'Hello World'
_.snakeCase('hello world')// → 'hello_world'
_.kebabCase('hello world')// → 'hello-world'
_.camelCase('hello world')// → 'helloWorld'

Padding

_.pad('abc', 3)           // → 'abc'
_.pad('abc', 8)           // → '   abc  '
_.pad('abc', 8, '_-')     // → '_-abc_-_'
_.padStart('abc', 3)      // → 'abc'
_.padStart('abc', 6)      // → '   abc'
_.padStart('abc', 6, '_-')// → '_-_abc'
_.padEnd('abc', 3)        // → 'abc'
_.padEnd('abc', 6)        // → 'abc   '
_.padEnd('abc', 6, '_-')  // → 'abc_-_'

Trim

_.trim('  str  ')         // → 'str' 
_.trimLeft('  str  ')     // → 'str  '
_.trimRight('  str  ')    // → '  str'

Etc

_.repeat('-', 2)        // → '--'
_.deburr('déjà vu')      // → 'deja vu'
_.trunc('hello world', 5)   // → 'hello...'

_.startsWith('abc', 'a')   // → true
_.endsWith('abc', 'c')     // → true

Objects

Keys and values

_.keys(obj)
_.values(obj)

Chaining

Chain and value

_([1, 2, 3])
  .reduce((total, n) => total + n)
  .map((n) => n * n)
  .tap(console.log)
  .thru((n) => n.reverse())
  .value()