Javascript，一个带有回调处理程序的对象，如何将其重写为 await/async 样式？

Question

我正在使用一个 api，它的对象提供回调处理程序，一个搜索功能。它看起来像这样:

function searchAndDoSomething(name){
    let searchObj = new APIobj(para1,{onSearchComplete:searchCompleteHandler});
    searchObj.search(name);
}
function searchCompleteHandler(result){
    doSomething(result);
}

我的目标是让它变成这样:

Async Main(){
      result = await searchAndDoSomething(name);
      searchCompleteHandler(result);  
}

但是如何重写searchAndDoSomething呢？

async searchAndDoSomething(name){
     return new Promise(function(resolve){
         let searchObj = new APIobj(para1,{onSearchComplete:resolve};//this will call a resolve function.
     //and
     resolve(name);//instead of searchObj.search will no effect too.
    })
}

Answer 1

您的尝试很接近，但由于您需要显式创建 promise (因为 APIobj 不需要)，因此您的函数没有理由异步。此外，您只想调用一次 resolve:

searchAndDoSomething(name) {
    return new Promise((resolve) => {
        const searchObj = new APIobj(para1, {onSearchComplete: resolve});
        searchObj.search(name);
    });
}

APIobj 大概有一种方法可以发出失败信号；如果是这样，你想调用 reject。例如，如果我猜测一个名为 onSearchError 的回调:

searchAndDoSomething(name) {
    return new Promise((resolve, reject) => {
        const searchObj = new APIobj(para1, {
            onSearchComplete: resolve,
            onSearchError: reject
        });
        searchObj.search(name);
    });
}

然后你可以像这样使用它:

async Main() { // Note it's `async`, not `Async`
    const result = await searchAndDoSomething(name); // note declaration
    searchCompleteHandler(result);  
}

或

async Main() {
    searchCompleteHandler(await searchAndDoSomething(name));  
}