javascript - 将变量传递给函数回调

Question

如何获取 fileDoesNotExist 回调的变量、url 和名称:

window.checkIfFileExists = function(path, url, name) {
  return window.requestFileSystem(LocalFileSystem.PERSISTENT, 0, (function(fileSystem) {
    return fileSystem.root.getFile(path, {
      create: false
    }, fileExists, fileDoesNotExist);
  }), getFSFail);
};

fileDoesNotExist = (fileEntry, url, name) ->
  downloadImage(url, name)

Answer 1

phoneGap的getFile函数有两个回调函数。您在这里使用 fileDoesNotExist 犯的错误是它应该调用两个函数，而不是引用一个变量。

像下面这样的东西会起作用:

window.checkIfFileExists = function(path, url, name) {
  return window.requestFileSystem(LocalFileSystem.PERSISTENT, 0, (function(fileSystem) {
    return fileSystem.root.getFile(path, {
      create: false
    }, 
    function(e) {
      //this will be called in case of success
    },
    function(e) {
      //this will be called in case of failure
      //you can access path, url, name in here
    });
  }), getFSFail);
};