html:

<p id="clear">刮風這天，我喜歡握著你手</p>

<input type="button" value="點擊" onclick="add()" />

<input type="button" value="點擊" onclick="hello()" />

js:

function $(id){

return document.getElementById(id);

}

window.onload = function(){

function add(){

document.getElementById('clear').style.display = 'none';

};

function hello(){

document.getElementById('clear').style.display = 'block';

}

}