chain

_.chain(value) # Ⓢ [Ⓣ][1]

Creates a lodash wrapper instance that wraps value with explicit method

chain sequences enabled. The result of such sequences must be unwrapped

with _#value.

Since

1.3.0

Arguments

1. value (*): The value to wrap.

Returns

(Object): Returns the new lodash wrapper instance.

Example

var users = [
  { 'user': 'barney',  'age': 36 },
  { 'user': 'fred',    'age': 40 },
  { 'user': 'pebbles', 'age': 1 }
];

var youngest = _
  .chain(users)
  .sortBy('age')
  .map(function(o) {
    return o.user + ' is ' + o.age;
  })
  .head()
  .value();
// => 'pebbles is 1'

---

plicitly called.

Lazy evaluation allows several methods to support shortcut fusion.

Shortcut fusion is an optimization to merge iteratee calls; this avoids

the creation of intermediate arrays and can greatly reduce the number of

iteratee executions. Sections of a chain sequence qualify for shortcut

fusion if the section is applied to an array and iteratees accept only

one argument. The heuristic for whether a section qualifies for shortcut

fusion is subject to change.

Chaining is supported in custom builds as long as the _#value method is

directly or indirectly included in the build.

In addition to lodash methods, wrappers have Array and String methods.

The wrapper Array methods are:

concat, join, pop, push, shift, sort, splice, and unshift

The wrapper String methods are:

replace and split

The wrapper methods that support shortcut fusion are:

at, compact, drop, dropRight, dropWhile, filter, find,

findLast, head, initial, last, map, reject, reverse, slice,

tail, take, takeRight, takeRightWhile, takeWhile, and toArray

The chainable wrapper methods are:

after, ary, assign, assignIn, assignInWith, assignWith, at,

before, bind, bindAll, bindKey, castArray, chain, chunk,

commit, compact, concat, conforms, constant, countBy, create,

curry, debounce, defaults, defaultsDeep, defer, delay,

difference, differenceBy, differenceWith, drop, dropRight,

dropRightWhile, dropWhile, extend, extendWith, fill, filter,

flatMap, flatMapDeep, flatMapDepth, flatten, flattenDeep,

flattenDepth, flip, flow, flowRight, fromPairs, functions,

functionsIn, groupBy, initial, intersection, intersectionBy,

intersectionWith, invert, invertBy, invokeMap, iteratee, keyBy,

keys, keysIn, map, mapKeys, mapValues, matches, matchesProperty,

memoize, merge, mergeWith, method, methodOf, mixin, negate,

nthArg, omit, omitBy, once, orderBy, over, overArgs,

overEvery, overSome, partial, partialRight, partition, pick,

pickBy, plant, property, propertyOf, pull, pullAll, pullAllBy,

pullAllWith, pullAt, push, range, rangeRight, rearg, reject,

remove, rest, reverse, sampleSize, set, setWith, shuffle,

slice, sort, sortBy, splice, spread, tail, take, takeRight,

takeRightWhile, takeWhile, tap, throttle, thru, toArray,

toPairs, toPairsIn, toPath, toPlainObject, transform, unary,

union, unionBy, unionWith, uniq, uniqBy, uniqWith, unset,

unshift, unzip, unzipWith, update, updateWith, values,

valuesIn, without, wrap, xor, xorBy, xorWith, zip,

zipObject, zipObjectDeep, and zipWith

The wrapper methods that are not chainable by default are:

add, attempt, camelCase, capitalize, ceil, clamp, clone,

cloneDeep, cloneDeepWith, cloneWith, conformsTo, deburr,

defaultTo, divide, each, eachRight, endsWith, eq, escape,

escapeRegExp, every, find, findIndex, findKey, findLast,

findLastIndex, findLastKey, first, floor, forEach, forEachRight,

forIn, forInRight, forOwn, forOwnRight, get, gt, gte, has,

hasIn, head, identity, includes, indexOf, inRange, invoke,

isArguments, isArray, isArrayBuffer, isArrayLike, isArrayLikeObject,

isBoolean, isBuffer, isDate, isElement, isEmpty, isEqual,

isEqualWith, isError, isFinite, isFunction, isInteger, isLength,

isMap, isMatch, isMatchWith, isNaN, isNative, isNil, isNull,

isNumber, isObject, isObjectLike, isPlainObject, isRegExp,

isSafeInteger, isSet, isString, isUndefined, isTypedArray,

isWeakMap, isWeakSet, join, kebabCase, last, lastIndexOf,

lowerCase, lowerFirst, lt, lte, max, maxBy, mean, meanBy,

min, minBy, multiply, noConflict, noop, now, nth, pad,

padEnd, padStart, parseInt, pop, random, reduce, reduceRight,

repeat, result, round, runInContext, sample, shift, size,

snakeCase, some, sortedIndex, sortedIndexBy, sortedLastIndex,

sortedLastIndexBy, startCase, startsWith, stubArray, stubFalse,

stubObject, stubString, stubTrue, subtract, sum, sumBy,

template, times, toFinite, toInteger, toJSON, toLength,

toLower, toNumber, toSafeInteger, toString, toUpper, trim,

trimEnd, trimStart, truncate, unescape, uniqueId, upperCase,

upperFirst, value, and words

Returns

(Object): Returns the new lodash wrapper instance.

Example

function square(n) {
  return n * n;
}

var wrapped = _([1, 2, 3]);

// Returns an unwrapped value.
wrapped.reduce(_.add);
// => 6

// Returns a wrapped value.
var squares = wrapped.map(square);

_.isArray(squares);
// => false

_.isArray(squares.value());
// => true

---