var CommentStripper = (function (window) {
 
    var SLASH = '/';
    var BACK_SLASH = '\\';
    var STAR = '*';
    var DOUBLE_QUOTE = '"';
    var SINGLE_QUOTE = "'";
    var NEW_LINE = '\n';
    var CARRIAGE_RETURN = '\r';
 
    var CommentStripper = function () {
 
    };
 
    CommentStripper.prototype = {
 
        string: '',
        length: 0,
        position: 0,
        output: null,
 
        getCurrentCharacter: function () {
            return this.string.charAt(this.position);
        },
 
        getPreviousCharacter: function () {
            return this.string.charAt(this.position - 1);
        },
 
        getNextCharacter: function () {
            return this.string.charAt(this.position + 1);
        },
 
        add: function () {
            this.output.push(this.getCurrentCharacter());
        },
 
        next: function () {
            this.position++;
        },
 
        atEnd: function () {
            return this.position >= this.length;
        },
 
        isEscaping: function () {
            if (this.getPreviousCharacter() == BACK_SLASH) {
                var offset = 1;
                var escaped = true;
                while ((this.position - offset) > 0) {
                    escaped = !escaped;
                    var current = this.position - offset;
                    if (this.string.charAt(current) != BACK_SLASH) {
                        return escaped;
                    }
                    offset++;
                }
                return escaped;
            }
            return false;
        },
 
        processSingleQuotedString: function () {
            if (this.getCurrentCharacter() == SINGLE_QUOTE) {
                this.add();
                this.next();
                while (!this.atEnd()) {
                    if (this.getCurrentCharacter() == SINGLE_QUOTE && !this.isEscaping()) {
                        return;
                    }
                    this.add();
                    this.next();
                }
            }
        },
 
        processDoubleQuotedString: function () {
            if (this.getCurrentCharacter() == DOUBLE_QUOTE) {
                this.add();
                this.next();
                while (!this.atEnd()) {
                    if (this.getCurrentCharacter() == DOUBLE_QUOTE && !this.isEscaping()) {
                        return;
                    }
                    this.add();
                    this.next();
                }
            }
        },
 
        processSingleLineComment: function () {
            if (this.getCurrentCharacter() == SLASH) {
                if (this.getNextCharacter() == SLASH) {
                    this.next();
                    while (!this.atEnd()) {
                        this.next();
                        if (this.getCurrentCharacter() == NEW_LINE || this.getCurrentCharacter() == CARRIAGE_RETURN) {
                            return;
                        }
                    }
                }
            }
        },
 
        processMultiLineComment: function () {
            if (this.getCurrentCharacter() == SLASH) {
                if (this.getNextCharacter() == STAR) {
                    this.next();
                    while (!this.atEnd()) {
                        this.next();
                        if (this.getCurrentCharacter() == STAR) {
                            if (this.getNextCharacter() == SLASH) {
                                this.next();
                                this.next();
                                return;
                            }
                        }
                    }
                }
            }
        },
 
        processRegex: function () {
            if (this.getCurrentCharacter() == SLASH) {
                if (this.getNextCharacter() != STAR && this.getNextCharacter() != SLASH) {
                    while (!this.atEnd()) {
                        this.add();
                        this.next();
                        if (this.getCurrentCharacter() == SLASH && !this.isEscaping()) {
                            return;
                        }
                    }
                }
            }
        },
 
        process: function () {
            while (!this.atEnd()) {
                this.processRegex();
                this.processDoubleQuotedString();
                this.processSingleQuotedString();
                this.processSingleLineComment();
                this.processMultiLineComment();
                if (!this.atEnd()) {
                    this.add();
                    this.next();
                }
            }
        },
 
        reset: function () {
            this.string = '';
            this.length = 0;
            this.position = 0;
            this.output = [];
        },
 
        strip: function (string) {
            this.reset();
            this.string = string;
            this.length = this.string.length;
            this.process();
            return this.output.join('');
        }
 
    };
 
    if (typeof define === 'function') {
        define('commentstripper', [], function () {
            return CommentStripper;
        });
    }
 
    return window.CommentStripper = CommentStripper;
 
})(window);

Usage is simple - create an instance and call .strip(string) to get back the de-commented string…

var cs = new CommentStripper();
console.log( cs.strip(someString) );

It's intended to be 100% effective - catching any valid comment, including:

var a = 10; // comment
var a = "http://www.github.com"; // more comments
var a = function(arg /*, ...rest */)

https://github.com/moagrius/stripcomments