javascript - 将 gulp 回调直接传递给 Promise 时出现异常

Question

我已经定义了 gulp 任务'clean-code'和函数'clean'，如下所示

gulp.task('clean-code', function (done) {
 var files = ...;
 clean(files, done);
});

function clean (path, done) {
 del(path).then(done);
}

并得到错误

/usr/local/bin/node /usr/local/lib/node_modules/gulp/bin/gulp.js --color --gulpfile /Users/[path to project]/Gulpfile.js clean-code
[11:45:04] Using gulpfile /Users/[path to project]/Gulpfile.js
[11:45:04] Starting 'clean-code'...
[11:45:04] Cleaning: ./.tmp/**/*.js,./build/**/*.html,./build/js/**/*.js
[11:45:04] 'clean-code' errored after 8.68 ms
[11:45:04] Error
    at formatError (/usr/local/lib/node_modules/gulp/bin/gulp.js:169:10)
    at Gulp.<anonymous> (/usr/local/lib/node_modules/gulp/bin/gulp.js:195:15)
    at emitOne (events.js:77:13)
    at Gulp.emit (events.js:169:7)
    at Gulp.Orchestrator._emitTaskDone (/Users/[path to project]/node_modules/gulp/node_modules/orchestrator/index.js:264:8)
    at /Users/[path to project]/node_modules/gulp/node_modules/orchestrator/index.js:275:23
    at finish (/Users/[path to project]/node_modules/gulp/node_modules/orchestrator/lib/runTask.js:21:8)
    at cb (/Users/[path to project]/node_modules/gulp/node_modules/orchestrator/lib/runTask.js:29:3)

但是，当我以下列方式重构函数“干净”时，一切正常

function clean (path, done) {
  var f = function () {
    done();
  };
  del(path).then(f);
}

我不明白区别在哪里以及为什么用 f 完成包装使任务正常工作

Answer 1

假设您正在使用这个库，那么为函数返回的 Promisedel实际上返回一个参数是毫无价值的paths。您可以像这样验证此参数是否存在：

function clean (path, done) {
    del(path).then(function(paths) {
        console.log(paths);
        done();
    });
}

在您的代码中：

function clean (path, done) {
    del(path).then(done);
}

会将paths参数转发给 done 函数，该函数会将其解释为导致应用程序崩溃的错误参数。通过调用done()自己，不会转发任何参数并且任务将被正确执行。