如何检查 javascript webbrowser 中的值是否已更改

var old = /*value*/function loop(){ if (/*value*/ != old){ //check if the value is not old  //do stuff } old = /*value*/ //set old to value requestanimationframe(loop) //loop every frame}requestanimationframe(loop) //wait a frame

var old = /*value*/function changed(){ var change = /*value*/ != old //check if the value is not old old = /*value*/ //set old to value return change //output change}