js simple sample code to determine whether js functions and variables exist

core code

 //Whether the specified function function exists isExitsFunction(funcName) { try { if (typeof(eval(funcName)) == "function") { return true; } } catch(e) {} return false;}//Whether the specified function exists Variable function isExitsVariable(variableName) { try { if (typeof(variableName) == "undefined") { //alert("value is undefined"); return false; } else { //alert("value is true"); return true; } } catch(e) {} return false;}

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