在 for 循环内部调用异步函数 [英] Call asynchronous function inside for loop

问题描述

var path;

for (var i = 0, c = paths.length; i < c; i++)
{
    path = paths[i];

    fs.lstat(path, function (error, stat)
    {
        console.log(path); // this outputs always the last element
    });
}

如何访问传递给 fs.lstat 函数的 path 变量?

How can I access the path variable, that was passed to fs.lstat function?

推荐答案

这是使用 .forEach() 而不是 for 循环来迭代值.

This is a perfect reason to use .forEach() instead of a for loop to iterate values.

paths.forEach(function( path ) {
  fs.lstat( path, function(err, stat) {
    console.log( path, stat );
  });
});

此外，您可以使用@Aadit 建议的闭包:

Also, you could use a closure like @Aadit suggests:

for (var i = 0, c = paths.length; i < c; i++)
{
  // creating an Immiedately Invoked Function Expression
  (function( path ) {
    fs.lstat(path, function (error, stat) {
      console.log(path, stat);
    });
  })( paths[i] );
  // passing paths[i] in as "path" in the closure
}

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