switch-js

switch-js

中文文档

Install

npm i switch-js

Example

const switcher = require('switch-js');
const valueToTest = 'foo';

switcher(valueToTest)
    .case('foo', () => console.log('foo!'))
    .case('bar', () => console.log('bar!'))
    .default(() => console.log('no match found in given cases!'))
    .always(() => console.log('this is cool!'));

// result:
// foo!
// this is cool!

Check for multiple cases:

switcher(valueToTest)
    .cases(['foo', 'bar'], () => console.log('foo or bar!'))
    .default(() => console.log('no match found in given cases!'));

// result: foo or bar!

Check if value is matched by a function:

switcher(valueToTest)
    .caseWhen(value => typeof value === 'string', () => console.log('a string!'))
    .caseWhen(value => typeof value === 'number', () => console.log('a number!'))
    .default(() => console.log('other datatypes!'));

// result: a string!

Use to to set value:

const valueInUppercase = switcher(valueToTest)
    .case('foo').to('FOO!')
    .case('bar').to('BAR!')
    .value('NO MATCH FOUND!');

// result: FOO!

// .value('NO MATCH FOUND!')
// has the same effect as
// .default().to('NO MATCH FOUND!').value()

Use mapTo to set the value by a function:

const valueInUppercase = switcher(valueToTest)
    .cases(['foo', 'bar']).mapTo(value => value.toUpperCase())
    .default().mapTo(value => value.toUpperCase() + ' IS NOT A MATCH!')
    .value();

// result: 'FOO'

API

switch(value)

start a switch chain

• value Value to check

case(caseValue[, matchedCallback][, notMatchedCallback])

The case method you know

• caseValue
• matchedCallback Function, optional. Invoked if caseValue equals deeply to value
• notMatchedCallback Function, optional. Invoked otherwise

cases(caseValues[, matchedCallback][, notMatchedCallback])

Check for multiple case values

• caseValues Array of caseValue
• matchedCallback Function, optional. Invoked if caseValues includes value
• notMatchedCallback Function, optional. Invoked otherwise

caseWhen(matcher[, matchedCallback][, notMatchedCallback])

Check by a function

• matcher A match function used to check if value is a match
• matchedCallback Function, optional. Invoked if matcher(value) returns a truthy value
• notMatchedCallback Function, optional. Invoked otherwise

default([noMatchFoundCallback, matchFoundCallback])

The default method you know

• noMatchFoundCallback Function, optional. Invoked if no match is found
• matchFoundCallback Function, optional. Invoked otherwise

always(callback)

Invoked anyway

• callback Function

to(valueToReturn)

Set a new value to return by value() if previous case is a match or it follows default()

• valueToReturn

mapTo(mapper)

Similiar to to() but set value by a mapper function

• mapper Function | String. If a string is passed, it will take as a path and invoke _.get(valueToTest, path) from lodash

value(defaultValue)

Return the value

• defaultValue Default value will return if no match is found