链式调用和延迟执行

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function arrange(name) {
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    // 任务队列
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    const tasks = []
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    // 添加任务
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    tasks.push(() => {
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        console.log(`${name} is notified`)
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    })
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    function doSomething(action) {
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        tasks.push(() => {
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            console.log(`Start to ${action}`)
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        })
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        return this
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    }
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    function wait(sec) {
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        tasks.push(() => new Promise(resolve => {
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            setTimeout(resolve, sec * 1000)
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        }))
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        return this
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    }
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    function waitFirst(sec) {
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       // 在任务队列的最前面插入一个任务
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       tasks.unshift(() => new Promise(resolve => {
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            setTimeout(resolve, sec * 1000)
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        }))
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        return this
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    }
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    async function execute() {
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        for (const t of tasks) {
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            await t()
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        }
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    }
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    return {
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        do: doSomething,
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        wait: wait,
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        waitFirst: waitFirst,
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        execute: execute
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    }
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}   
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arrange('William').execute()  
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// > William is notified
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arrange('William').do('commit').execute()
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// > William is notified
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// > Start to commit
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arrange('William').wait(5).do('commit').execute()
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// > William is notified
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// 等待5秒
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// > Start to commit
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arrange('William').waitFirst(5).do('commit').execute()
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// 等待5秒
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// > William is notified
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// > Start to commit

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William is notified
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William is notified
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William is notified
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Start to commit
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William is notified
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Start to commit
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Start to commit