如何在javascript中同步调用一组函数

问题描述：

我正在研究一个需要获取一些数据并对其进行处理的javascript项目，但是我在JavaScript的异步特性方面遇到了麻烦.我想要做的是如下所示.

I am working on a javascript project that needs to get some data and process it, but I am having trouble with the asynchronous nature of JavaScript. What I want to be able to do is something like the following.

//The set of functions that I want to call in order
function getData() {
    //gets the data
}

function parseData() {
    //does some stuff with the data
}

function validate() {
    //validates the data
}

//The function that orchestrates these calls 
function runner() {
    getData();
    parseData();
    validate();
}

在这里，我希望每个函数在完成下一个调用之前都等待完成，因为我遇到了程序尝试在检索数据之前对其进行验证的情况.但是，我也希望能够从这些函数中返回一个值进行测试，因此我不能让这些函数返回一个布尔值来检查完成情况.如何让javascript等待该函数运行完成，然后再继续下一个调用?

Here I want each function to wait for completion before going on to the next call, as I am running into the situation where the program attempts to validate the data before it has been retrieved. However, I also want to be able to return a value from these functions for testing, so I can't have these functions return a boolean value to check completion. How can I make javascript wait on the function to run to completion before moving on to the next call?

答

使用承诺:

//The set of functions that I want to call in order
function getData(initialData) {
  //gets the data
  return new Promise(function (resolve, reject) {
    resolve('Hello World!')
  })
}

function parseData(dataFromGetDataFunction) {
  //does some stuff with the data
  return new Promise(function (resolve, reject) {
    resolve('Hello World!')
  })
}

function validate(dataFromParseDataFunction) {
  //validates the data
  return new Promise(function (resolve, reject) {
    resolve('Hello World!')
  })
}

//The function that orchestrates these calls 
function runner(initialData) {
    return getData(initialData)
        .then(parseData)
        .then(validate)
}

runner('Hello World!').then(function (dataFromValidateFunction) {
    console.log(dataFromValidateFunction);
})

它们不仅易于掌握，而且从代码可读性的角度来看完全有意义.在此处了解更多信息.如果您在浏览器环境中，建议使用此 polyfill.

Not only are they easy to grasp, it makes total sense from a code readability stand point. Read more about them here. If you are in a browser environment, I recommend this polyfill.

如何在javascript中同步调用一组函数

相关推荐