要使代码按您所描述的那样工作，则需要将回调函数作为参数传递给.series()。例如：

Gulp.task('clean',function () {
    console.log('Clean');
    return Gulp.src("./dbSchema/*")
        .pipe(VinylPaths(Del));
})

Gulp.task('copy:db',Gulp.series(clean,function () {
    console.log('Copy DB');
    return Gulp.src("./db/*")
        .pipe(Gulp.dest("./dbSchema"));
}))

Gulp.task('default',Gulp.series(copy:db,function () {
    console.log('defaulp');
    return TypeScriptProject.src()
        .pipe(TypeScriptProject())
        .js.pipe(Gulp.dest('dist'));
}));

恕我直言，拥有三个完全独立的任务会更简单：

Gulp.task('clean',function () {
    console.log('Clean');
    return Gulp.src("./dbSchema/*")
        .pipe(VinylPaths(Del));
});

Gulp.task('copy:db',function () {
    console.log('Copy DB');
    return Gulp.src("./db/*")
        .pipe(Gulp.dest("./dbSchema"));
});

Gulp.task('default',function () {
    console.log('defaulp');
    return TypeScriptProject.src()
        .pipe(TypeScriptProject())
        .js.pipe(Gulp.dest('dist'));
});

，然后使用以下任一方法呼叫他们：

Gulp.task('default',gulp.series(clean,copy:db,js));

或

Gulp.task('default',gulp.parallel(copy:db,js)));

希望有帮助：）

附加说明：

1. gulp / vars的命名约定通常为camelCase，例如：gulp和typeScriptProject而非Gulp或TypeScriptProject。

2. 您可以使用gulp.

完全消除编写var {gulp,task,src,dest,watch,series,parallel} = require('gulp');的麻烦。

3. 与其直接定义任务，不如使用CommonJS exports模块表示法声明任务来使代码更易于阅读。

4. 如果您在使用引号时保持一致，则可以使生活更轻松一些，而不是混合使用单打和双打。两者都允许

遵循Gulp自己的文档也许是一个起点，their sample code on github提供了一些设置基本gulpfile的好例子。

如果将所有内容都打包，就会得到：

/*
 * Example of requires with gulp methods also requiring gulp.
 */
var { 
    gulp,parallel,watch 
}           = require('gulp'),vinylPaths  = require('vinyl-paths'),// may not be required,see note in clean func.
del         = require('del'),ts          = require('gulp-typescript');

/*
 * Added a basic TypeScript Project so the example is complete and could run.
 */
var typeScriptProject = ts.createProject({
    declaration: true
});

/*
 * Your tasks converted to plain/standard js functions.
 */
function clean () {
    return src('dbSchema/*')
        .pipe(vinylPaths(del));

    // Looking at your example code the vinylPaths is redundant,// as long as you’re using del ^2.0 it will return its promise,// so you could replace the above with:
    return del([ 'dbSchema' ]);
}

function copyDb () {
    return src('db/*')
        .pipe(dest('dbSchema'));
}

function scripts () {
    // example src path
    return src('lib/*.ts')
        .pipe(typeScriptProject())
        .pipe(dest('dist'));
}

/*
 * By defining all the tasks separately it makes it really clear how the tasks will run.
 */
var build = gulp.series (
    clean,gulp.parallel (
        copyDb,scripts
    )
);

/*
 * Example of using `exports` module notation to declare tasks.
 */
exports.clean = clean;
exports.copyDb = copyDb;
exports.scripts = scripts;
exports.build = build;

/*
 * Good practise to define the default task as a reference to another task.
 */
exports.default = build;