如何在按钮单击时运行js脚本

Question

How to run this script with button click?

I don't know how to write code for a button and connect it with the code below.

<div id="rez" style="display: none;">BRAVO!</div> 

<script>
function showElement(id) {
    document.getElementById(id).style.display = "block";
}

window.onload = function ShowHide() {
    var legend = document.getElementById("LEGEND").innerHTML;

    if(legend.indexOf("100%") != -1) showElement("rez");

}
</script>

Answer 1

一个简单的谷歌搜索将产生这类问题的答案： http : //www.w3schools.com/jsref/event_onclick.asp