javascript - What does it mean in parentheses word (EVENT),in html,and why I have to write it down?without that (event) all the code will not work -
html <div id="cube" onmousemove= cordinate(event)></div> <p id= "text"></p> css #cube{ width: 300px; height: 300px; border: 2px solid black; } and js function cordinate(a){ var x = a.clientx; var y = a.clienty; var cor = "cordinates: " + x + " " + y; document.getelementbyid("text").innerhtml= cor; this code mouse-cordinate of div "cube" in onxxx attribute, event variable contains object information action caused handler triggered. instance, in onmousemove , event object contains mouse coordinates in clientx , clienty properties. you can read detailed documentation event object here . this site has more details on how event object passed event handlers, depending on how define them.