Thanks for your answer!
I'm confused about your example, why would the first comparison 'f1==f2'
return false if they refer to the same function?
I checked the v8 document and found two member functions from v8 Function
class, which are* int ScriptID() *and *int GetIdentityHash().*
Could I use them to distinguish two v8::Local<v8::Function>? If two
v8::Local<v8::Function> refer to the same function, would this two function
return the same value?
Best regards!
On Wednesday, March 22, 2017 at 9:09:22 AM UTC-4, Jakob Kummerow wrote:
>
> The == operator on v8::Local compares if two Locals are referring to the
> same JavaScript object (which can, of course, be a function) by object
> identity (aka reference). (Structural equality is the opposite!)
>
> Note that two functions can contain the same code, but have different
> object identity:
>
> function GetFun() {
> return function() { /* do something funny */ }
> }
> var f1 = GetFun();
> var f2 = GetFun();
> f1 === f2; // false!
> f1.property = "yay";
> f2.property === undefined; // true!
>
> If you had v8::Locals for f1 and f2, then local1 == local2 would be false.
>
> On Tue, Mar 21, 2017 at 7:15 PM, Hanyun Tao <taoha...@gmail.com
> <javascript:>> wrote:
>
>> Hi all,
>>
>> I'm new to v8 and I want to know more about the equality check (==)
>> between two v8::Local<v8::Object>.
>>
>> Currently I'm using instrumenting chromium browser. In chromium,
>> registered event listeners are stored inside a map like data structure, and
>> I can use the getListenerObject() method to get the v8::Local<v8::Object>
>> correspond to each event listener, which could be a function reference, or
>> reference to an object with handleEvent property.
>>
>> My goal is to tell if two different event listener will invoke the same
>> javascript or not. Someone told me that I can do this by comparing two
>> v8::Local<v8::Object> by value. I followed the suggestion and implements a
>> function that returns unique integer ID for unique v8::Local<v8::Object>
>> value. However when I test it on real webpage, I found that almost every
>> event listeners are mapped to the same ID.
>>
>> I'm not confident with this result so I want to ask a question here. What
>> does the equality check (==) between two v8::Local<v8::Object> check? Does
>> it implies that the two object are structurally equal (contains the same
>> function/object reference), or it means something else?
>>
>> Best regards,
>>
>>
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>
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