Allow AMP to be compiled with full property obfuscation

[cramforce]

@erwinmombay and me are preparing the AMP code base for more aggressive optimizations in the closure compiler.

Right now only private properties are obfuscated. Soon, among other things, all properties will be obfuscated unless we stop them.

That means stuff like

foo.mutateElement might become a.a;

saving lots of bytes :)

However, it also means that if you so something like

JSON.stringify({type: 'abc'})

then type might be obfuscated, but the party that parsrs the json (Say youtube) might have had no idea and break.

For this reason you must now always quote properties like {'type': 'abc'} or foo['type'] when accessing properties that come from an external source. That is unless you created an "Extern" for the type (beyond the scope of this email).

I submitted a bunch of PRs
#9876, #9960

that use the type system to enforce y'all doing this right as much as possible.

It might, however, miss some stuff. E.g. json['foo'].bar is not an error, but would break. You have to write json['foo']['bar']
There might be more cases that the typing doesn't catch. If you find a case where you think a property should be quoted, but the compiler doesn't yell at you, please ping me.

The cases where we need to be careful are:

• JSON.parse, stringify
• postMessage and the message event
• fetch messages and responses
• parsing or generating query strings
• polyfilling APIs (make sure to case polyfills to the defined extern type)
• did I missing anything? Please comment on Allow AMP to be compiled with full property obfuscation #9876

Tasks:

• Audit all calls to JSON.parse
• Audit all calls to JSON.stringify
• Change types of sendMessage and friends.
• fetch body
• parseQueryString
• Polyfills need to use correct externed types.
• Tighten type of event.data for Message events.
• Audit amp-analytics config
• Audit amp-social share config
• dataset and classlist

[alanorozco]

What about setStyles? Uses the object key names for the style props.

[cramforce]

@alanorozco Should be covered by externs.

[alanorozco]

@cramforce AFAICT externs would cover that from setStyles -> native API, right? What about the actual uses of setStyles? Like opacity in setStyles(x, { 'opacity': 0 });

[cramforce]

@alanorozco We'll need to try, but basically because the compiler is very conservative it will assume that this might be an externed object.

[ampprojectbot]

This issue seems to be in Pending Triage for awhile. @cramforce Please triage this to an appropriate milestone.

[ampprojectbot]

This issue seems to be in Pending Triage for awhile. @cramforce Please triage this to an appropriate milestone.

[ampprojectbot]

This issue seems to be in Pending Triage for awhile. @cramforce Please triage this to an appropriate milestone.