How do I optimize Javascript with Closure Compiler and keep function names?

Question

I have a javascript-file (lib.js) and I want to use some of the functions in an web page but I don't want to load the full lib.js.

However, I have not figured out how to do what I want. I want to use command line.

lib.js

function dog() {
    return 'Fido';
}

function famous_human() {
    return 'Winston';
}

function human() {
    return famous_human();
}

code-calling-functions-in-lib.js

alert(human());

Desired result, lib-compiled.js

function a() {return 'Winston';}function human() {return a();}

Function dog is removed since I don't use it.
Function famous_human is is optimized.
Function human has its original name since I want to call it from other code.
No code from code-calling-functions-in-lib.js

.

java -jar compiler.jar --compilation_level ADVANCED_OPTIMIZATIONS --js lib.js --XXXXXXXX code-calling-functions-in-lib.js --js_output_file lib-compiled.js

Is there a simple answer to my question?

Chad Killingsworth · Accepted Answer · 2013-08-27 18:28:12Z

2

You can export human:

function human() {
    return famous_human();
}

window['human'] = human;

More information on exports

Since exporting symbols blocks dead-code elimination, a best practice is to keep the project-specific exports in a separate file and not included in your library.

Example

Library Source - liba.js

function dog() {
  return 'Fido';
}

function famous_human() {
  return 'Winston';
}

function human() {
  return famous_human();
}

Project Specific Exports - project_exports.js

window['human'] = human;

Compile command

java -jar compiler.jar \
  --compilation_level ADVANCED_OPTIMIZATIONS \
  --js liba.js \
  --js project_exports.js \
  --js project_source.js \
  --js_output_file project_compiled.js

edited Aug 27, 2013 at 18:28

Chad Killingsworth

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answered Aug 27, 2013 at 15:08

Paul

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7 Comments

user2473324 Over a year ago

Ok, but can you be more specific? I might be really stupid but I do need an idiot proof example. I have read a lot and tried a lot of examples on this issue but I don't get it to work.

Paul Over a year ago

Yes @user2473324 As a first try to get it working you can put that line in lib.js. Try it out on closure-compiler.appspot.com/home

Paul Over a year ago

@user2473324 When I compile the three function from your question with that extra export line I get the result: window.human=function(){return"Winston"};, which would allow you to call human() from other scripts, since window is the global context.

Paul Over a year ago

I believe @Chad Killingsworth is more familiar with Closure than me, so perhaps he could give some advice too.

Chad Killingsworth Over a year ago

@user2473324 There is too much to explain in a comment, so I added the example to the answer.

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How do I optimize Javascript with Closure Compiler and keep function names?

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Example

Library Source - liba.js

Project Specific Exports - project_exports.js

Compile command

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1 Answer 1

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Library Source - liba.js

Project Specific Exports - project_exports.js

Compile command

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