add exposefunc feature #1222

hillguo · 2022-12-12T08:49:49Z

In some scenarios, need to bind go func to the browser environment. when js called, the function executes in go process and returns a Promise
refer https://pptr.dev/api/puppeteer.page.exposefunction/

ZekeLu · 2022-12-13T03:31:35Z

Thank you! Can you add some tests for the new feature?

ZekeLu

I will take a careful look later.

expose.go

ZekeLu

This is the second round. Please take a look. Thank you!

expose.go

js/expose.js

expose_test.go

hillguo · 2023-02-01T13:06:31Z

According to your suggestion, the implementation method has been modified.

as an action to call
remove the lock
modify test code

Please review it again

ZekeLu · 2023-02-06T09:34:38Z

I'm sorry that it takes a little long to review. I just want to let you know that I'm still working on it.

I'm confusing by this feature. IIUC, runtime.AddBinding adds a new js function to the page. It does not replace an existing function in the page. That means this feature is only useful when the web page is written with the mind that the page will be accessed by a browser that is controlled by a Go application, which will expose a js function to be called by the web page. I can not think of such kind of use cases.

Do you have a real world use case to share? Thank you!

hillguo · 2023-02-07T08:40:11Z

@ZekeLu Yes, I think so, too.
There are two scenarios:

The browser knows in advance that there is a callable function
After chromedp exposes the function, chromedp initiatively calls

Scenario 1, in order to ensure that the function must exist, it usually needs to be exposed before the page js is loaded. (AddScriptToEvaluateOnNewDocument) does this, but it needs to take effect after navigation.

My business scenario is cloud Web game rendering.
A brief introduction to the exposed functions:

GameLoaded. After the game is loaded, js calls this function, and when chromedp receives it, it calls the logic to capture the game screen.
HeartbeatReport. Monitor the normal operation of the game. The reason why we expose go heartbeat function to browser is that heartbeat service in the private network does not have https, but we do not want to use the public network https.
VideoSave. The data recorded by the browser is saved locally.

The two most important points for this feature:

Js environment call
go environment execution

ZekeLu · 2023-02-07T10:39:41Z

Thank you for the explanation!

I'm not sure I understand it. But it seems that in the use cases, the js environment does not need the returned value from the Go environment. If this is the case, runtime.AddBinding is enough.

hillguo · 2023-02-07T11:37:04Z

In my scenario, I don't need a return value and runtime.AddBinding is enough.
Other scenes For example:

you need a complex encryption algorithm function without js implementation or js running is inefficient;
read local text content

I'm sorry that my example is not very accurate , more examples can search for puppeteer-related usage
exposefunction

Finally, I think this feature is similar to JSBridge, a means of communication, but not necessary.

ZekeLu · 2023-02-15T06:52:09Z

I have put the suggested changes into this commit: ZekeLu@feef44e. The tests could be improved too, but I haven't touched it yet.

Please take a look. If you agree with the suggested changes, please apply them to your commit.

Please note that I'm still not sure whether this function is useful enough to be shipped by chromedp.

review

hillguo · 2023-02-16T07:02:36Z

Thank you for the code optimization. It's more elegant.😊

ZekeLu

Thank you for your hard work too!

I have added some more comments.

I think some of them are hard to address.

I'm inclined to convert this feature to an example and add it to https://github.com/chromedp/examples instead. If we provide it as an example, we don't have to address the reminding issues. And we can add it back to the package if someone find it useful and there are attracting use cases. What do you think?

ZekeLu · 2023-02-16T07:44:01Z

expose.go

+// Note:
+// 1. This is the lite version of puppeteer's [page.exposeFunction].
+// 2. It adds "chromedpExposeFunc" to the page's window object too.
+// 3. The exposed function survives page navigation until the tab is closed?


// 3. The exposed function survives page navigation until the tab is closed?

I think we have to answer this question.

There is not way to revert this action. I think we should mention this.

yes, no way to revert this action.

`Runtime.removeBinding` does not remove binding function from global object but unsubscribes current runtime agent from Runtime.bindingCalled notifications.

Not only the binding, but also the scripts that will be evaluated on new document (page.AddScriptToEvaluateOnNewDocument). I know that we can store the ScriptIdentifier and remove it later, but it will make the code complicated.

It only takes effect on the page after navigation. The target(Page) hasn't changed. this kind of behavior should be understood

Most state does not survive page navigation. But the scripts that the expose action uses survive page navigation and there is no way to stop that (unless the tab is closed), so this behavior should be documented.

expose.go

js/expose.js

expose the function to all frames

hillguo · 2023-02-20T06:34:46Z

expose.go

+	})
+}
+
+func evaluateOnAllFrames(script string) Action {


@ZekeLu expose the function to all frames. please check this function.

We need a test case to cover it.

Test cases have been added and a bug has been fixed

fix closure bug && add exposeToAllFrames test case

modify note

lindowx · 2023-07-25T11:13:43Z

expose.go

+)
+
+// ExposedFunc is the function type that can be exposed to the browser env.
+type ExposedFunc func(args string) (string, error)


I think it would be more flexible if the args parameter was defined as an interface{} type.

The reason for this design is that it is consistent with the cdp bindingCalled event parameter, which can only pass string.
Refer to Runtime.bindingCalled
https://chromedevtools.github.io/devtools-protocol/tot/Runtime/#event-bindingCalled

PARAMETERS name string payload string var payload struct { Type string `json:"type"` Name string `json:"name"` Seq int64 `json:"seq"` Args string `json:"args"` }```

hillguo added 2 commits December 12, 2022 15:50

add exposefunc feature

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add exposefunc feature

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ZekeLu reviewed Dec 13, 2022

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hillguo added 2 commits December 13, 2022 18:21

--test=optimize the code and add test cases

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--test=optimize the code and add test cases

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ZekeLu reviewed Dec 14, 2022

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hillguo added 5 commits December 29, 2022 18:08

modify test examples

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modify test examples

5e7067d

change expose feature as chromedp's action

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change expose feature as chromedp's action

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Add trailing new line

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ZekeLu mentioned this pull request Feb 15, 2023

Support a way to listen for javascript events #184

Closed

hillguo and others added 3 commits February 16, 2023 11:15

Merge branch 'chromedp:master' into master

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review

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Merge pull request #1 from hillguo/zekelu/expose

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ZekeLu requested changes Feb 16, 2023

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hillguo and others added 2 commits February 20, 2023 14:26

expose the function to all frames

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Merge pull request #2 from hillguo/zekelu/expose

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expose the function to all frames

hillguo commented Feb 20, 2023

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hillguo and others added 3 commits February 20, 2023 21:07

fix closure bug && add exposeToAllFrames test case

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Merge pull request #3 from hillguo/zekelu/expose

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fix closure bug && add exposeToAllFrames test case

modify note

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Merge pull request #4 from hillguo/zekelu/expose

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modify note

ZekeLu mentioned this pull request Jul 10, 2023

EventBindingCalled Not Triggering #1337

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lindowx reviewed Jul 25, 2023

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Merge branch 'chromedp:master' into master

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add exposefunc feature #1222

add exposefunc feature #1222

hillguo commented Dec 12, 2022

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add exposefunc feature #1222

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add exposefunc feature #1222

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ZekeLu commented Dec 13, 2022 •

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