javascript - setinterval seems to accelerate -

i have setinterval within function, on first click seems fine, every subsequent click accelerates timer. don't understand why.

function startgame() {     var myvar=setinterval(function(){mytimer()},100); } 

when clicking second time, first interval works, because of event happens twice in 100ms. try this:

var myvar; function startgame() {     if(myvar)         clearinterval(myvar);     myvar=setinterval(function(){mytimer()},100); } 

or:

var myvar; function startgame() {     if(!myvar)         myvar=setinterval(function(){mytimer()},100); }