add after ary assign assignIn assignInWith assignWith at before bind bindAll bindKey camelCase capitalize castArray ceil chain chunk clamp clone cloneDeep cloneDeepWith cloneWith compact concat conformsTo countBy create curry curryRight debounce deburr defaults defaultsDeep defer delay difference divide drop dropRight each eachRight endsWith entries entriesIn eq escape every extend extendWith fill filter find findIndex findKey findLast findLastIndex findLastKey first flatMap flatMapDeep flatMapDepth flatten flattenDeep flattenDepth flip floor forEach forEachRight forIn forInRight forOwn forOwnRight fromPairs functions functionsIn get groupBy gt gte has hasIn head inRange includes indexOf initial intersection invert invertBy invoke invokeMap 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 isSymbol isTypedArray isUndefined isWeakMap isWeakSet join kebabCase keyBy keys keysIn last lastIndexOf lowerCase lowerFirst lt lte map mapKeys mapValues max maxBy mean meanBy memoize merge mergeWith min minBy multiply negate nth omit omitBy once orderBy overArgs pad padEnd padStart parseInt partial partialRight partition pick pickBy pull pullAll pullAllBy pullAllWith pullAt random rearg reduce reduceRight reject remove repeat replace rest result reverse round sample sampleSize set setWith shuffle size slice snakeCase some sortBy sortedIndex sortedIndexOf sortedLastIndex sortedLastIndexOf sortedUniq split spread startCase startsWith subtract sum sumBy tail take takeRight tap template throttle thru toArray toFinite toInteger toLength toLower toNumber toPairs toPairsIn toPlainObject toSafeInteger toString toUpper transform trim trimEnd trimStart truncate unary unescape union uniq uniqBy uniqWith unset unzip unzipWith update updateWith upperCase upperFirst values valuesIn without words wrap wrapperAt wrapperChain wrapperCommit wrapperFlatMap wrapperLodash wrapperNext wrapperPlant wrapperReverse wrapperToIterator wrapperValue xor zip zipObject zipObjectDeep zipWith

Lodash _.chain

Overview

lodash is a popular open-source JavaScript utility library that provides a wide range of methods to simplify working with arrays, strings, objects, and functions. One of the most powerful methods in lodash is _.chain(). This method allows developers to chain multiple lodash methods together to transform data in a clean and concise way.

_.chain() creates a lodash wrapper object that allows the application of chainable sequence of methods to any value. Instead of applying a series of different methods on a value, such as an array or object, separately, _.chain() offers a functional paradigm that allows developers to create a chain of methods that results in the desired outcome for that value.

The advantage of using _.chain() over regular lodash methods is that it provides flexibility and simplicity in manipulating data. Each method in the chain processes the result of the previous method, allowing for easy data transformations. This formatting is done in a way that promotes readability in terms of coding.

One major benefit of _.chain() is that it helps to eliminate complex code repetition, thus reducing the possibility of human error. _.chain() acts as an abstraction layer allowing developers to deal with transformations in a simple and clear manner.

The chain method returns a wrapped object, which means that in order to get the final result, you need to call .value() which will execute the methods in the chain and return the final value. It's essential to call .value() at the end of the chain as the execution of the chain methods is deferred until a final result can be computed.

Here's an example of how you can use _.chain() to filter, map, sort, and reduce the values of an array:

const users = [
  { name: 'John', age: 27 },
  { name: 'Jane', age: 21 },
  { name: 'Mike', age: 32 },
  { name: 'Lisa', age: 19 }
];

const result = _.chain(users)
  .filter(user => user.age >= 21)
  .map(user => ({ fullName: `${user.name} Doe`, age: user.age }))
  .sortBy('age')
  .reduce((acc, user) => acc + user.age, 0)
  .value();

// result: 59

Here, we first filter the array to exclude any users under the age of 21. We then map each user object to a new object that includes their full name and age. Next, we sort the array in ascending order of age. Finally, we use the reduce() method to calculate the sum of ages of all users, with an initial value of 0.

In summary, _.chain() is a powerful method that allows developers to perform complex data transformations in a simple and readable manner. Its functional paradigm eliminates complex code repetition, resulting in reduced human error while promoting maintainable, scalable code.