如何在gulp任务之间共享参数？

Question

I'd like to share a set of parameters that describe the current execution flow. This is how I am doing it at the moment:

let taskError;

gulp.task('pre-watch', () => {
    taskError = false; 
});

gulp.task('task-a', () => {
    console.log('OK');
});

gulp.task('task-b', () => {
    console.log('Error');

    taskError = true;
});

gulp.task('task-c', () => {
    console.log('Error', taskError);

    if (!taskError) {
        throw new Error('Was expecting taskError to be true.');
    }
});

gulp.task('watch', () => {
    gulp.watch('./**/*', [
        'pre-watch',
        'task-a',
        'task-b',
        'task-c'
    ]); 
});

This approach works great until we run into issues with parallelism, ie

• gulp.watch detected a change.
• pre-watch done, task-a done, task-b done ...
• gulp.watch detected a change.
• pre-watch resets taskError .
• task-c throws Error .

Is there a way to pass parameters within the current task execution flow?

Answer 1

As you have found out gulp tasks by default run in parallel. The best gulp plugin ever is run-sequence

npm i -SD run-sequence

https://www.npmjs.com/package/run-sequence

Very popular, 4k+ downloads a day. Its a temp fix until gulp 4 is released which will give more control over parallelism.

It allows you to do ...

'task1', ['task2', 'task3'], 'task4'

That is ...

Run task 1

Then run task 2 and task 3 in parallel

When both 2 and 3 are complete then run task 4

This fixes your parallelism issue :)

Not sure this is the best way of sharing params.