使用OS.file在javascript中为文件添加前缀

知道为什么从未调用成功的

onSuccess

吗

文件系统

rob@work:~$ cat test.txt
hello
hello2
rob@work:~$ pwd
/home/rob

插件代码

var filePath = '/home/rob/test.txt',
  combinedString = 'new file content';

const {TextDecoder, TextEncoder, OS} = Cu.import("resource://gre/modules/osfile.jsm", {});

OS.File.read(filePath).then(function(data) { // check if specified file exists

  console.log(data)
  function onSuccess(array) { // prepend to file
    let text = new TextDecoder().decode(array);
    let encodedArray = new TextEncoder().encode(combinedString + text);
    console.log('exists: ' + combinedString + text);
    var promise = OS.File.writeAtomic(filePath, encodedArray);
    promise.then(
      function() {
        console.log('success');
      },
      function(ex) {
        console.log('fail');
      }
    );
  }
}, function(ex) { // file doesn't exist, create a new one
  if (ex.becauseNoSuchFile) {
    let encodedArray = new TextEncoder().encode(combinedString);
    var promise = OS.File.writeAtomic(filePath, encodedArray);
    console.log('new: ' + combinedString + text);
    promise.then(
      function() {
        console.log('success');
      },
      function(ex) {
        console.log('fail');
      }
    );
  }
});

这是console中的唯一输出

console.log: savetexttofile: Uint8Array {"0":104,"1":101,"2":108,"3":108,"4":111,"5":10,"6":104,"7":101,"8":108,"9":108,"10":111,"11":50,"12":10}
Total time: 5.596181 seconds
Program terminated successfully.

---

您确实意识到您只是在声明您的

onSuccess

函数，而从未使用过它，即它没有被用作read的then调用的第一个参数

let promise = OS.File.read(filePath);
promise = promise.then(function onSuccess(contents) {
  let text = new TextDecoder().decode(contents);

  combinedString = combinedString + '\n\n' + text;

  if (System.getPlatform().indexOf('win') >= 0)
        combinedString = combinedString.replace(/[\n]/g, '\r\n');

  let encodedArray = new TextEncoder().encode(combinedString);

  var promise = OS.File.writeAtomic(filePath, encodedArray);
  promise.then(
    function() {
      console.log('success');
    },
    function(ex) {
      console.log('error');
    }
  );
  return true;
}, 
function onError(reason) {
  if (System.getPlatform().indexOf('win') >= 0)
    combinedString = combinedString.replace(/[\n]/g, '\r\n');
    let encodedArray = new TextEncoder().encode(combinedString);
    if (reason.becauseNoSuchFile()) {
      var promise = OS.File.writeAtomic(filePath, encodedArray);
      promise.then(
         function() {
          console.log('success');
        },
        function(ex) {
          console.log('error');
        }
      );
    return false;
  }
});