javascript - Cannot read property 'parentNode' of null. Error i get in console - 


 var button1 = document.getelementbyid("start"); var button2 = document.getelementbyid("stop"); var timegraph = document.getelementbyid("ceas"); var lapbutton = document.getelementbyid("lap"); var lame = document.getelementbyid("test"); var time = 0; var resetstart = 0; var myinterval; var body = document.getelementbyid("body"); var action = document.getelementbyid("lappara"); function start() {     if (resetstart == 0) {         resetstart = 1;         running();         button1.innerhtml = "pause";     }     else {         resetstart = 0;         button1.innerhtml = "resume";         clearinterval(myinterval);     } } function reset() {     time = 0;     resetstart = 0;     button1.innerhtml = "start";     timegraph.innerhtml = "00:00:00:00";     clearinterval(myinterval);     var aux = action.parentnode;     aux.removechild(action); } function ongoing() {     time++;     var hours = math.floor(time / 100 / 60 / 60);     var minutes = math.floor(time / 100 / 60 % 60);     var seconds = math.floor(time / 100 % 60);     var hundreds = math.floor(time / 10 % 10);     var thousands = time % 10;     if (hours < 10) {         hours = "0" + hours;     }     if (minutes < 10) {         minutes = "0" + minutes;     }     if (seconds < 10) {         seconds = "0" + seconds;     }     timegraph.innerhtml = hours + ":" + minutes + ":" + seconds + ":" + hundreds + thousands; } function running() {     if (resetstart == 1) {         myinterval = setinterval(ongoing, 10);     }     else {         timegraph.innerhtml = "00:00:00:00";     } } function lap() {     var n = document.createelement("p");     n.setattribute("id", "lappara");     var text = document.createtextnode(timegraph.innerhtml);     n.appendchild(text);     body.insertbefore(n, action); }

whenever call reset() function error above. code supposed stopwatch , lap() function creates laps. looked solutions none seemed work. please me if can

i assume can call reset() once next time call error appears. because of aux.removechild(action). delete action , try it's parentnode - that's problem is.


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