<script?type="text/javascript">?
function?hs(){??
?????var?d;
?//獲取第一個(gè)輸入框的值???
?var?a=?document.getElementById("txt1");
?//獲取第二個(gè)輸入框的值
?var?b=?document.getElementById("txt2");
?//獲取選擇框的值
?var?c=?document.getElementById("select");????
?//獲取通過下拉框來選擇的值來改變加減乘除的運(yùn)算法則???
??switch?(c){???????
???case?"+":??????
????d?=?parseInt(a)+parseInt(b);?????
????break;?
?????
???case?"-":
???d=a-b;?
???break;
?????
???case?"*":?
???d=a*b;????????
???break;???
?
??default:???
??d=a/b;????}???
??//設(shè)置結(jié)果輸入框的值??????
????document.getElementById('fruit').value=d;????}??
????????</script>?
?</head>??
?<body>???
?<input?type='text'?id='txt1'?/>??
???<select?id='select'>
???<option?value='+'>+</option>
???<option?value="-">-</option>
???<option?value="*">*</option>
???<option?value="/">/</option>???</select>??
????<input?type='text'?id='txt2'?/>????
????<input?type='button'?value='?=?'?/>?<!--通過?=?按鈕來調(diào)用創(chuàng)建的函數(shù),得到結(jié)果-->?
???????<input?type='text'?id='fruit'?/>????</body>
2020-01-04
document.getElementById(
"txt1"
);獲取的是id為txt1的<input>這個(gè)標(biāo)簽元素
document.getElementById(
"txt1"
).value;獲取的是ID為txt1的<input>這個(gè)標(biāo)簽元素之間的value值.
如果標(biāo)簽元素之間沒有value屬性則
document.getElementById(
"txt1"
).value;沒有有返回值.
提示NaN的話,個(gè)人判斷是d?=?parseInt(a)+parseInt(b);? 的值解析錯(cuò)了.