@uirouter/core/common/hof | @uirouter/react
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Module @uirouter/core/common/hof

Higher order functions

These utility functions are exported, but are subject to change without notice.



Const propEq

propEq: Function = curry((name: string, _val: any, obj: any) => obj && obj[name] === _val)

Given a property name and a value, returns a function that returns a boolean based on whether the passed object has a property that matches the value let obj = { foo: 1, name: "blarg" }; let getName = propEq("name", "blarg"); getName(obj) === true


Const all

  • all(fn1: Predicate<any>): (Anonymous function)
  • Check if all the elements of an array match a predicate function


    • fn1: Predicate<any>

      a predicate function fn1

    Returns (Anonymous function)

    a function which takes an array and returns true if fn1 is true for all elements of the array


Const any

  • any(fn1: Predicate<any>): (Anonymous function)


  • compose(): (Anonymous function)
  • Given a varargs list of functions, returns a function that composes the argument functions, right-to-left given: f(x), g(x), h(x) let composed = compose(f,g,h) then, composed is: f(g(h(x)))

    Returns (Anonymous function)


  • curry(fn: Function): Function
  • Returns a new function for Partial Application of the original function.

    Given a function with N parameters, returns a new function that supports partial application. The new function accepts anywhere from 1 to N parameters. When that function is called with M parameters, where M is less than N, it returns a new function that accepts the remaining parameters. It continues to accept more parameters until all N parameters have been supplied.

    This contrived example uses a partially applied function as an predicate, which returns true if an object is found in both arrays.

    // returns true if an object is in both of the two arrays
    function inBoth(array1, array2, object) {
      return array1.indexOf(object) !== -1 &&
             array2.indexOf(object) !== 1;
    let obj1, obj2, obj3, obj4, obj5, obj6, obj7
    let foos = [obj1, obj3]
    let bars = [obj3, obj4, obj5]
    // A curried "copy" of inBoth
    let curriedInBoth = curry(inBoth);
    // Partially apply both the array1 and array2
    let inFoosAndBars = curriedInBoth(foos, bars);
    // Supply the final argument; since all arguments are
    // supplied, the original inBoth function is then called.
    let obj1InBoth = inFoosAndBars(obj1); // false
    // Use the inFoosAndBars as a predicate.
    // Filter, on each iteration, supplies the final argument
    let allObjs = [ obj1, obj2, obj3, obj4, obj5, obj6, obj7 ];
    let foundInBoth = allObjs.filter(inFoosAndBars); // [ obj3 ]


    • fn: Function

    Returns Function

Const eq

  • eq(value: any): (Anonymous function)
  • Given a value, returns a Predicate function that returns true if another value is === equal to the original value


    • value: any

    Returns (Anonymous function)


  • invoke(fnName: string): Function
  • invoke(fnName: string, args: any[]): Function

Const is

  • is<T>(ctor: { constructor: any }): (Anonymous function)
  • Given a class, returns a Predicate function that returns true if the object is of that class

    Type parameters

    • T


    Returns (Anonymous function)

Const not

  • not(fn: Predicate<any>): (Anonymous function)
  • Given a function that returns a truthy or falsey value, returns a function that returns the opposite (falsey or truthy) value given the same inputs


    Returns (Anonymous function)


Const parse

  • parse(name: string): any
  • Given a dotted property name, returns a function that returns a nested property from an object, or undefined let obj = { id: 1, nestedObj: { foo: 1, name: "blarg" }, }; let getName = prop("nestedObj.name"); getName(obj) === "blarg" let propNotFound = prop("this.property.doesnt.exist"); propNotFound(obj) === undefined


    • name: string

    Returns any


  • pattern(struct: Function[][]): Function
  • Sorta like Pattern Matching (a functional programming conditional construct)

    See http://c2.com/cgi/wiki?PatternMatching

    This is a conditional construct which allows a series of predicates and output functions to be checked and then applied. Each predicate receives the input. If the predicate returns truthy, then its matching output function (mapping function) is provided with the input and, then the result is returned.

    Each combination (2-tuple) of predicate + output function should be placed in an array of size 2: [ predicate, mapFn ]

    These 2-tuples should be put in an outer array.

    // Here's a 2-tuple where the first element is the isString predicate
    // and the second element is a function that returns a description of the input
    let firstTuple = [ angular.isString, (input) => `Heres your string ${input}` ];
    // Second tuple: predicate "isNumber", mapfn returns a description
    let secondTuple = [ angular.isNumber, (input) => `(${input}) That's a number!` ];
    let third = [ (input) => input === null,  (input) => `Oh, null...` ];
    let fourth = [ (input) => input === undefined,  (input) => `notdefined` ];
    let descriptionOf = pattern([ firstTuple, secondTuple, third, fourth ]);
    console.log(descriptionOf(undefined)); // 'notdefined'
    console.log(descriptionOf(55)); // '(55) That's a number!'
    console.log(descriptionOf("foo")); // 'Here's your string foo'


    • struct: Function[][]

      A 2D array. Each element of the array should be an array, a 2-tuple, with a Predicate and a mapping/output function

    Returns Function


  • pipe(...funcs: Function[]): (obj: any) => any
  • Given a varargs list of functions, returns a function that is composes the argument functions, left-to-right given: f(x), g(x), h(x) let piped = pipe(f,g,h); then, piped is: h(g(f(x)))


    • Rest ...funcs: Function[]

    Returns (obj: any) => any

      • (obj: any): any
      • Parameters

        • obj: any

        Returns any

Const prop

  • prop(name: string): (Anonymous function)
  • Given a property name, returns a function that returns that property from an object let obj = { foo: 1, name: "blarg" }; let getName = prop("name"); getName(obj) === "blarg"


    • name: string

    Returns (Anonymous function)

Const val

  • val<T>(v: T): (Anonymous function)

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