myPromise | TS 版 Promise ，promise-polyfill 实现过程详解 | Reactive Programming library

The property accessor has precedence over the await operator, so you need to add parentheses:

I try to fix, what you mean?

Check if the "ids" is already an array. If it is, the "{ Requirement_id: [filteredIds]}" , should be [{ Requirement_id: filteredIds }].

Agreeing with the comments, you should avoid the Promise constructor antipattern and never use await in the executor of a new Promise!

You should write either

There are no problems with this approach, using a promise queue is a standard pattern that will solve your problem.

While your code does work fine, I would recommend to avoid the Promise constructor antipattern:

Just remove www. from script urls.

You should use http://skulpt.org/js/skulpt.min.js instead of http://www.skulpt.org/js/skulpt.min.js

Actually that has nothing to do with the promise. When you add a button and log the arrays, you see that 'foo' is in 'itemsB' as well, it's just not rendered. From the Svelte Docs

Because Svelte's reactivity is based on assignments, using array methods like .push() and .splice() won't automatically trigger updates. A subsequent assignment is required to trigger the update.
The according tutorial

You can use .push() if it's followed by a reassignment of the array to itself

JS promise gives you the option to run code asynchronously. So you signal the JS engine that you would like to preform an action once another action is finished. Since actions can be successful or not promises can be resolved (resolve) or rejected (reject). For handling success you use then for handling fail you use catch, optional after both you can use finally.

So when you declare a promise the JS engine knows it is not something you need now, rather later. It will start the execution but will relate to its result later on. After starting the promise action it will runs through the rest of the synchronous commands, in you case all except the then. Once dohe ne it will check if it has promises that already had been resolved, if yes it will execute the relevant than.

The resolve() puts the then of the promise to the callback queue. Later on when the call-stack will be empty the engine will handle that. Same would go for reject() but with catch.

If you would like to keep a cleaner syntax I recommend to check async-await.

*also note that your setTimeout is not giving you anything. If you put console.log in it, it will also be shown only after the 'finish'.

One way you can achieve this is to attach a scroll listener when the scrollTo is called. Then remove the listener once the desired location is reached. This way you can ensure that the highlight occurs only when the desired scroll position is reached.

I've created a very simple implementation of this as an example:

Codepen Example