关闭编译ADVANCED_OPTIMIZATIONS抱怨使用此方法

Question

I have a Gruntfile.js as below with closure compiler config ,

module.exports = function(grunt) {

grunt.initConfig({

    pkg: grunt.file.readJSON('package.json'),
     'closure-compiler': {
         jstracker: {
              closurePath: '/usr/local/',
              js: [
                'src/js/banner.js',
                'src/js/lib/json.js',
                'src/js/lib/jstz.js',
                'src/js/init.js',
                'src/js/helpers.js',
                'src/js/lib/sha1.js',
                'src/js/lib/murmur.js',
                'src/js/lib/base64.js',
                'src/js/tracker.js',
                'src/js/prayagupd.js',
                'src/js/constructor.js'
               ],
              jsOutputFile: 'dist/<%= pkg.name %>.min.js',
              options: {
                      compilation_level: 'ADVANCED_OPTIIZATIONS',
                      warning_level:"DEFAULT",
                      language_in: 'ECMASCRIPT5_STRICT'
               }
          }
    },

    qunit: {
        files: ['tests/**/*.html']
    },
    jshint: {
        files: ['Gruntfile.js', 'src/**/*.js', 'tests/*.js'],
        options: {
            // options here to override JSHint defaults
            globals: {
                jQuery: true,
                console: true,
                module: true,
                document: true
            }
        }
    },
    watch: {
        files: ['<%= jshint.files %>'],
        tasks: ['jshint', 'qunit']
    }
});

grunt.loadNpmTasks('grunt-contrib-uglify');
grunt.loadNpmTasks('grunt-contrib-jshint');
grunt.loadNpmTasks('grunt-contrib-qunit');
grunt.loadNpmTasks('grunt-contrib-watch');
grunt.loadNpmTasks('grunt-contrib-concat');
grunt.loadNpmTasks('grunt-closure-compiler');

grunt.registerTask('test', ['jshint', 'closure-compiler', 'qunit']);
grunt.registerTask('default', ['jshint', 'closure-compiler', 'qunit']);

};

When I execute grunt to generate minified js, I see minified version at target folder,

$ ls -lh dist/
total 44K
-rw-rw-r-- 1 prayagupd prayagupd  27K Jul  6 16:34 prayagupd.min.js
-rw-rw-r-- 1 prayagupd prayagupd  514 Jul  6 16:34 prayagupd.min.js.report.txt

But with following 4 warnings all pointing to use of this , that later pops up as error ( Uncaught ReferenceError: JSON2 is not defined ) while using in browser.

src/js/lib/json.js:26: WARNING - dangerous use of the global this object
if (!this.JSON2) {
     ^
src/js/lib/json.js:27: WARNING - dangerous use of the global this object
    this.JSON2 = {};
    ^
src/js/leakers.js:1995: WARNING - dangerous use of the global this object
            this.setContextProperty("leaksId", leaksId);
            ^
src/js/leakers.js:2002: WARNING - dangerous use of the global this object
            this.setContextProperty("userId", userId);
            ^
0 error(s), 4 warning(s)

SIMPLE_OPTIMIZATIONS level works fine though.

Offending source codes

//src/js/lib/json.js:26
// Create a JSON object only if one does not already exist. We create the
// methods in a closure to avoid creating global variables.
if (!this.JSON2) {
    this.JSON2 = {};
}

and,

   //src/js/leakers.js

   /**
    * Set context properties, properties which are used with every event
    */
    setContextProperty: function(name, value) {
        context[name] = value;
    },

    /**
    * Set leaks ID
    */
    setLeakesId: function(leakesId) {
        this.setContextProperty("leakesId", leakesId);
    },

    /**
    * Set user ID
    */
    setUserId: function(userId){
        this.setContextProperty("userId", userId);
    }

Two things I need help to fix;

1) ask closure to ignore this , which doesn't seem possible under ADVANCED_OPTIMIZATIONS

or

2) Find ways to replace this to and get working.

Answer 1

The compiler is basically warning that you are using "this" in a way that it is unsure about (you may be accidentally be using the global this) and maybe incompatible with advanced compilation. You want to verify that that the "this" value is going to be correct and indicate that to the compiler by using a @this annotation.

This warning is documented here: https://developers.google.com/closure/compiler/docs/error-ref