faster.js

// 1. get browser
// 2. patch js
// 3. ???
// 4. profit

navigator.sayswho = (function(){
    var ua = navigator.userAgent, tem, M = ua.match(/(opera|chrome|safari|firefox|msie|trident(?=\/))\/?\s*(\d+)/i) || [];
    if(/trident/i.test(M[1])){
        tem=  /\brv[ :]+(\d+)/g.exec(ua) || [];
        return 'IE '+(tem[1] || '');
    }
    if(M[1]=== 'Chrome'){
        tem= ua.match(/\b(OPR|Edge)\/(\d+)/);
        if(tem!= null) return tem.slice(1).join(' ').replace('OPR', 'Opera');
    }
    M = M[2]? [M[1], M[2]]: [navigator.appName, navigator.appVersion, '-?'];
    if((tem= ua.match(/version\/(\d+)/i))!= null) M.splice(1, 1, tem[1]);
    return M.join(' ');
})();


var CHROME = 1, IE = 2, FF = 3, OPERA = 4, OTHER = 5;
var browser = navigator.sayswho.toUpperCase();
browser = !browser.indexOf('chrom') ? 1
        : !browser.indexOf('ie')    ? 2
        : !browser.indexOf('firef') ? 3
        : !browser.indexOf('oper')  ? 4
        : /* unknown or default */    5;

String.prototype.replaceAll = (function(ptn, sub) {
  switch(browser) {
    case CHROME:
    case IE:
    case FF:
    case OPERA:
      return function(ptn){ return this.split(ptn).join(sub;  }
      break;
    default:
      return function(ptn){ return this.replace(/[\-\[\]\/\{\}\(\)\*\+\?\.\\\^\$\|]/g, "\\$&").replace(new RegExp(ptn, 'gm'), sub); }
      break;
  }
})(browser);