如何从文件中读取数据，将其传递给另一个函数并返回函数的返回值？ [重复]

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这个问题在这里已有答案：

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I'm trying to return arr when final() is called....

我试图在调用final（）时返回arr ....

  function final(){
        var arr;
        fs.readFile("/my/path/", 'utf8' ,(err, data) => {
            arr = parsing(data);
            arr.splice(-1,1);


      });
        return arr;
    }

It keeps returning undefined. Even though arr inside the readFile brackets gives me an array...

它不断返回undefined。即使readFile括号内的arr给我一个数组......

The possible duplicate discusses printing whereas I need a value to use somewhere else. How can I use the value arr in another function/module?

可能的重复讨论打印，而我需要一个值来使用其他地方。如何在另一个函数/模块中使用值arr？

2 个解决方案

#1

readFile is async function you need to do this

readFile是你需要执行此操作的异步函数

function final(){
        var arr;
        fs.readFile("/my/path/", 'utf8' ,(err, data) => {
            arr = parsing(data);
            arr.splice(-1,1);
            return arr;
        });

}

#2

or pass a callback function to final function

或者将回调函数传递给最终函数

function callback(arr) {
//do something with arr
}

function final(callback) {
    var arr;
    fs.readFile("/my/path/", 'utf8' ,(err, data) => {
        arr = parsing(data);
        arr.splice(-1,1);
        callback(arr);
    });
}

As @Farhan Yassen's answer won't result correct behavior due to the async nature.

由于异步性质，@ Farhan Yassen的答案不会导致正确的行为。

And also, you can always use synchronous version of the readFile with readFileSync

而且，您始终可以将readFile的同步版本与readFileSync一起使用

#1