<html><head><metacharset="UTF-8"><title></title></head><body><h1>简易计算器</h1><tableborder="1"style="position:center;"><tr><th>第一个数</th><td><inputid="fir"type="text"/></td></tr><tr><th>第二个数</th><td><inputid="sec"type="text"/></td></tr><tr><tdcolspan="2"><buttononclick="add()">+</button><buttononclick="substract()">-</button><buttononclick="multiply()">*</button><buttononclick="divide()">/</button></td></tr><tr><tdcolspan="2"><pid="result"></p></td></tr></table></body></html><script>var res;//保存计算结果//加法函数functionadd(){
//document.getElementById().value 根据id属性,获取用户输入的值var first = document.getElementById("fir").value;var second = document.getElementById("sec").value;
res =Number(first)+Number(second);//这里"+"两端必须Number类型转换,否则当成字符串连接sent(res);//sent() 调用方法,设置结果}//减法函数functionsubstract(){
var first = document.getElementById("fir").value;var second = document.getElementById("sec").value;
res = first - second;sent(res);}//乘法函数functionmultiply(){
var first = document.getElementById("fir").value;var second = document.getElementById("sec").value;
res = first * second;sent(res);}//计算除法的方法functiondivide(){
var first = document.getElementById("fir").value;var second = document.getElementById("sec").value;
res = first / second;sent(res);}functionsent(re){
//计算结果显示函数
document.getElementById("result").innerHTML = re;}</script>