js判断指定函数、变量是否存在的方法

//判断是否存在指定函数 function isExitsFunction(funcName) {try {if (typeof (eval(funcName)) == "function") {return true;}} catch (e) {}return false;}// 判断是否存在指定变量 function isExitsVariable(variableName) {try {if (typeof (variableName) == "undefined") {return false;} else {return true;}} catch (e) {}return false;}