<input name="txt" id="txt" type="text" /><input name="" type="button" onclick="addNum()" value="查看" /> <script type="text/javascript"> function $(id){ return document.getElementById(id); } function addNum(){ var val = $("txt").value; var num = parseInt(val)+1; var i=1; for(var o=2; o<num; o++){ i = i+o; } $("txt").value = i; } </script>
<html> <head> <script> function count(){ var val = document.getElementById("val1").value; if(val && !isNaN(val)){ var toAdd = new Number(val); var result = 0; for(var i = 1;i<=toAdd;i++){ result += i; } document.getElementById("result").value=result; } } </script> </head> <body> 1+2+3+..+<input type="text" id="val1" size="3"/>=<input type="text" id="result" size="5"/><input type="button" value="计算" onclick="count()"/> </body> </html>
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就是这样啦,这个应该是你要的功能 [code] <script> function sum(){ var num = document.getElementById("num").value; var result = 0; for(var i = 1;i <= num;i++){ result += i; } document.getElementById("result").innerText = result; } </script> <input type="text" id="num" /> <button onclick="sum()">计算</button><br/> 结果:<span id="result"></span> [/code]
看看这个,应该是你要的<script> function sum(){ var num = document.getElementById("num").value; var result = 0; for(var i = 1;i <= num;i++){ result += i; } document.getElementById("result").innerText = result; } </script> <input type="text" id="num" /> <button onclick="sum()">计算</button><br/> 结果:<span id="result"></span>
<script type="text/javascript">
function $(id){
return document.getElementById(id);
}
function addNum(){
var val = $("txt").value;
var num = parseInt(val)+1;
var i=1;
for(var o=2; o<num; o++){
i = i+o;
}
$("txt").value = i;
}
</script>
<head>
<script>
function count(){
var val = document.getElementById("val1").value;
if(val && !isNaN(val)){
var toAdd = new Number(val);
var result = 0;
for(var i = 1;i<=toAdd;i++){
result += i;
}
document.getElementById("result").value=result;
}
}
</script>
</head>
<body>
1+2+3+..+<input type="text" id="val1" size="3"/>=<input type="text" id="result" size="5"/><input type="button" value="计算" onclick="count()"/>
</body>
</html>
[code]
<script>
function sum(){
var num = document.getElementById("num").value;
var result = 0;
for(var i = 1;i <= num;i++){
result += i;
}
document.getElementById("result").innerText = result;
}
</script>
<input type="text" id="num" />
<button onclick="sum()">计算</button><br/>
结果:<span id="result"></span>
[/code]
function sum(){
var num = document.getElementById("num").value;
var result = 0;
for(var i = 1;i <= num;i++){
result += i;
}
document.getElementById("result").innerText = result;
}
</script>
<input type="text" id="num" />
<button onclick="sum()">计算</button><br/>
结果:<span id="result"></span>