Switchify

Simple and powerful functional alternative for JavaScript switch and if ternary operator expressions.

Installation

npm i -S switchify

Usage

const result = check(10)
      .matches(10)
        .then(val => '10 matched!')
        .else('not matched!');
// result: '10 matched!'

First let's call check() to set an expression to match

check(10)

After use one of matching functions:

• matches
• in
• else

matches

matches function accepts:

• number
• string
• boolean
• null
• NaN
• Object
• Array
• Class
• RegExp
• Date
• function

If function was passed as argument it will be evaluated. If both expression and a matching value are functions they will be stringified and compared.

const result = check({foo: 'hi'})
      .matches(() => ({foo: 'hi'}))
        .then(val => 'callback result matched!')
        .else('not matched!');      
// result: 'callback result matched!'

const foo = () => 'hi';
const bar = () => 'hi';
const result = check(foo)
      .matches(bar)
        .then(val => 'functions matched!')
        .else('not matched!');
// result: 'functions matched!'

If RegExp was passed it will test it against matching expression if it's not a RegExp also, in this case a stringified values will be compared.

const result = check('usd')
      .matches(/^[\w]{3}$/)
        .then(val => 'usd matched!')
        .else('not matched!');
// result: 'usd matched!'

const result = check(new RegExp('[\w]{2}'))
      .matches(/[w]{2}/)
        .then(val => 'RegExp matched!')
        .else('not matched!');
// result: 'RegExp matched!'

If object or array was passed it will do deep comparison:

const result = check({foo: 'hi'}])
      .matches({foo: 'hi'})
        .then(val => 'object matched!')
        .else('not matched!');
// result: 'object matched!'

const result = check([33,44])
      .matches([33,44])
        .then(val => 'array matched!')
        .else('not matched!');
// result: 'array matched!'

in

Checks if expression is included in passed array

const result = check(10)
      .in([3, 10, 5])
        .then(val => '10 in [3, 10, 5]!')
        .else('not matched!');
// result: '10 in [3, 10, 5]!'
      

else

to finish you need to call a mandatory function else()

const result = check(10)
      .in([1,2])
        .then('matched')
        .else(val => 'not matched!');
// result: 'not matched!'

You can pass it a callback as well.

and

Use .and to chain expression with logical and

let result = check('hi')
      .matches(val => val[0] === 'h')
      .and
      .in(['hi', 'hello'])
        .then(val => 'value matched!')
        .else('not matched!');
// result: 'value matched!'

or

Use .or to chain expression with logical or

let result = check(10)
      .matches(11)
      .or
      .matches(100)
        .then(val => 'value matched!')
        .else('not matched!');
// result: 'not matched!'

Nested expressions

Use .also keyword to add a nested clauses

let result = check('hi')
      .matches(val => val[0] === 'h')
        .also
          .matches(val => val.length === 2)
            .then(val => 'nested value matched!')
            .else('nested not matched!')
      .else('not matched!');
// result: 'nested value matched!'