中文README

Installation

npm

npm i -S args-promise

yarn

yarn add args-promise

CDN

<script src="https://cdn.jsdelivr.net/npm/args-promise@1.3.0"></script>

Or you can import the ES Modules compatible build like this:

<script type="module">
  import ArgsPromise from 'https://cdn.jsdelivr.net/npm/args-promise@1.3.0/dist/ArgsPromise.esm.min.js'
</script>

Usage

ArgsPromise behaves like native Promise.

const ArgsPromise = require('args-promise').default

new ArgsPromise((resolve, reject) => {
    resolve('foo', 'bar')
}).then((a, b) => {
    console.log(a, b)  // --> 'foo' 'bar'
})

new ArgsPromise((resolve, reject) => {
    reject('foo', 'bar')
}).then((a, b) => {
    console.log(a, b)  // not executed
}).catch((a, b) => {
    console.log('catched', a, b)  // --> 'catched' 'foo' 'bar'
})

If you want to pass multiple arguments to the handle function of next then(), you can return an Array like this:

new ArgsPromise(resolve => {
    resolve()
}).then(() => {
    return ['foo', 'bar']
}).then((a, b) => {
    console.log(a, b)  // --> 'foo' 'bar'
})

await and the methods of Promise (such as Promise.allSettled()) is also effective for ArgsPromise.

let p1 = new ArgsPromise(resolve => {
    setTimeout(() => {
        resolve()
    }, 1000)
})
let p2 = new ArgsPromise(resolve => {
    setTimeout(() => {
        resolve()
    }, 3000)
})
Promise.allSettled([p1, p2])
    .then(() => {
        console.log('allSettled')  // print 'allSettled' after 3s
    })

async function foo() {
    await new ArgsPromise((resolve) => {
        setTimeout(() => {
            resolve()
        }, 3000)
    })
    console.log('bar')
}
foo()  // print 'bar' after 3s

But there is a problem that you can only get the first argument by using Promise.allSettled() and await directly like this:

let p = new ArgsPromise(resolve => {
  resolve(1, 2, 3, 4, 5)
})
Promise.allSettled([p]).then(result => {
  console.log(result[0].value)  // --> 1
})

let args = await new ArgsPromise(resolve => {
  resolve(1, 2, 3, 4, 5)
})
console.log(args)  // --> 1

To get all the arguments, you can use .pack() like this:

let p = new ArgsPromise(resolve => {
  resolve(1, 2, 3, 4, 5)
}).pack()
Promise.allSettled([p]).then(result => {
  console.log(result[0].value)  // --> [ 1, 2, 3, 4, 5 ]
})

let args = await new ArgsPromise(resolve => {
    resolve(1, 2, 3, 4, 5)
}).pack()
console.log(args)  // --> [ 1, 2, 3, 4, 5 ]

Referring to await-to-js ，ArgsPormise provides .to() to help you to handle simple errors like this:

let p1 = new ArgsPromise((resolve, reject) => {
    resolve('hello', 'world')
})
let [err1, values1] = await p1.to()
if(err1) {
    console.log(err1)
} else {
    console.log(values1)  // --> [ 'hello', 'world' ]
}


let p2 = new ArgsPromise((resolve, reject) => {
    reject('err')
})
let [err2, values2] = await p2.to()
if(err2) {
    console.log(err2)  // --> [ 'err' ]
} else {
    console.log(values2)
}

The executor function which passed into ArgsPromise's constructor receives the third parameter. It is a function that allows you to set some resident variables. In the same Promise Chain, resident variables will always be passed into the handle function of .then(), .catch() and .finally().

There is an example of setting and receiving resident variables:

new ArgsPromise((resolve, reject, resident) => {
    resident('resident-0', 'resident-1')
    resolve(1, 2, 'hello')
}).then((...args) => {
    console.log(...args)    // --> 1 2 'hello' 'resident-0' 'resident-1'
    return ['foo', 'bar']
}).then((...args) => {
    console.log(...args)    // --> 'foo' 'bar' 'resident-0' 'resident-1'
    return 123
}).then((...args) => {
    console.log(...args)    // --> 123 'resident-0' 'resident-1'
}).then((...args) => {
    console.log(...args)    // --> 'resident-0' 'resident-1'
})