regexp.escape function of javascript

RegExp.escape() function example

RegExp.escape = (function() {
    var punctuationChars = /([.*+?|/(){}[\]\\])/g;
    return function(text) {
        return text.replace(punctuationChars, '\\$1');
    }
})();

var str = RegExp.escape('a+b/c*d$ ^{.}');
var reg = new RegExp(str);

References

1. http://simonwillison.net/2006/Jan/20/escape