javascript - 从 Promise 访问 'this' 之外的 JavaScript

Question

我什至不知道如何表达我的问题，在我完全搞砸之前，这是我的代码:

className.prototype.requestData = function (start, end) {
    client.server.functionName(parameters)
        .done(function (msg) {
            if (msg) {                
                this.process(msg); //this belongs to client, not className as I want
            }
        })
        .fail(function (error) {
            console.log('failed: ' + error);
        });
}

如你所见，我需要调用process来对返回的数据进行操作，我不想使用我为它定义的变量，我想使用this，我猜这是不可能的，有没有更好的方法来实现我的目标？

谢谢

Answer 1

如果你在 ES6 中工作，你可以使用 async/await:

className.prototype.requestData = async function (start, end) {
    try {
        let result = await client.server.functionName(parameters);
        if (result ) {                
            this.process(result);
        }
    } catch (err) {
        console.log('failed: ' + err);
    }
}

如果你想“链接”它们，你可以这样做:

try {
    let result = await client.server.functionName(parameters);
    if (result) {                
        this.process(result);
    }
    // You can just call each in succession
    let other_result = await client.server.someOtherAsyncFunc(other_params);
    if(other_result) {
        // Do more stuff
    }
} catch (err) {
    console.log('failed: ' + err);
}

// You can still call more promise-based functions after the try-catch block
let some_result = await client.server.yetAnotherAsyncFunc(more_params);
// Do other stuff with some_result