parallel-to-serial

Parallel task based on Promise converted to serial task

examples

``js
const parallelToSerial = require('parallel-to-serial')

function square(val) {
return new Promise((resolve, reject) => {
setTimeout(() => {
const result = Math.pow(val, 2)
console.log(${val} -> ${result})
resolve(result)
}, 1000)
})
}

let timer
const data = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
const task = data.map(val => () => {
clearTimeout(timer)
// 并发多条时不打印-----
// 保证为下一次调用切片时，在切片中间打印-----
timer = setTimeout(() => console.log('--------'))
return square(val)
})

console.log('并发量为1')
parallelToSerial(task, 1)
.then(val => {
console.log('整个任务执行完成：', data, '->', val)
})
.then(() => {
console.log('\n并发量为3')
return parallelToSerial(task, 3)
})
.then(val => {
console.log('整个任务执行完成：', data, '->', val)
})
`

Output results：

`
并发量为1
--------
1 -> 1
--------
2 -> 4
--------
3 -> 9
--------
4 -> 16
--------
5 -> 25
--------
6 -> 36
--------
7 -> 49
--------
8 -> 64
--------
9 -> 81
--------
10 -> 100
整个任务执行完成： [ 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 ] -> [ 1, 4, 9, 16, 25, 36, 49, 64, 81, 100 ]

并发量为3
--------
1 -> 1
2 -> 4
3 -> 9
--------
4 -> 16
5 -> 25
6 -> 36
--------
7 -> 49
8 -> 64
9 -> 81
--------
10 -> 100
整个任务执行完成： [ 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 ] -> [ 1, 4, 9, 16, 25, 36, 49, 64, 81, 100 ]
``