<SCRIPT LANGUAGE="JavaScript"> var total = 0 var play = false // (element == clicked checkbox object) function display(element) { // assign instance of Date object representing current time var now = new Date() // if the game has not started yet if (!play) { // game starts now play = true // milliseconds since 1970 for time at beginning startTime = now.getTime() } // if more than 20 seconds have passed since startTime was last set if (now.getTime() - startTime > 20000) { // reject modification (make "read-only") element.checked = !element.checked // terminate function return } // if the clicked checkbox is now checked if (element.checked) // increment total total++ else // decrement total total-- // display total in text object element.form.num.value = total } function restart(form) { // set global variables back to initial values total = 0 play = false // uncheck all 100 checkboxes for (var i = 1; i <= 100; ++i) { // uncheck current checkbox form.elements[i].checked = false } } // --> </SCRIPT> <SCRIPT LANGUAGE="JavaScript"> <!--// immediate script (executed before the other script because it is deferred) document.write("<FORM><CENTER>") document.write('<INPUT TYPE="text" VALUE="0" NAME="num" SIZE=10 onFocus="this.blur()"><BR>') document.write("<HR SIZE=1 WIDTH=40%>") // use loop to create a 10 x 10 square of checkboxes for (var i = 0; i < 10; ++i) { for (var j = 0; j < 10; ++j) { // write checkbox with "display(this)" as event handler script document.write('<INPUT TYPE="checkbox" onClick="display(this)">') } document.write("<BR>") } document.write("<HR SIZE=1 WIDTH=40%>") // create button to call restart function to restart game document.write('<INPUT TYPE="button" VALUE="restart" onClick="restart(this.form)">') document.write("</CENTER></FORM>") // --> </SCRIPT>