JavaScript function won't fire on button click
Question
I've just started teaching myself JavaScript and am doing some basic exercises. Right now I'm trying to make a function that takes in three values and prints out the largest. However, the function refuses to fire upon button click. I tried making a separate, very simple function just for debugging and it refuses to fire as well. I've written other practice functions in almost the exact same manner (they had two parameters as opposed to three) that work fine. Any insight would be greatly appreciated.
<!DOCTYPE HTML>
<html>
<head>
<script type = "text/javascript">
<!--
//Define a function Max() that takes three numbers as
//arguments and returns the largest of them.
function Boo(){
document.write("boo");
alert("boo");
}
function Max(p1, p2, p3){
document.write(p1+p2+p3);
alert('BOO!')
document.write(document.getElementById('value1').value);
var max = Number(p1);
v2 = Number(p2):
v3 = Number(p3);
if (v2 > max)
max = v2;
if (v3 > max)
max = v3;
document.write(max);
}
-->
</script>
</head>
<body>
<form>
<input type="text" id="value1" name="value1"/><br />
<input type="text" id="value2" name="value2"/><br />
<input type="text" id="value3" name="value3"/><br />
<input type = "button"
onclick="Boo()"
value = "Compare!"/>
<!-- onclick="Max(document.getElementById('value1').value,
document.getElementById('value2').value,
document.getElementById('value3').value)" -->
</form>
</body>
</html>
4 answers
solution1
5 ACCPTED 2012-05-31 14:36:58
v2 = Number(p2):
should be
v2 = Number(p2);
Also, look into the developer tools for whatever browser you are using to find simple syntax errors like this. (In most browsers you can press F12).
solution2
2 2012-05-31 14:38:31
chrome developer tool says it has syntax error!
v2 = Number(p2):
should be:
v2 = Number(p2);
solution3
1 2012-05-31 14:36:06
您的javascript函数已用<!-- -->注释掉
solution4
0 2012-05-31 15:06:55
This is all you need:
var elements = document.getElementsByName('to_compare');
var elementsAsArray = [].slice.call(elements);
var numberValues = elementsAsArray.map(function(x) {
return Number(x.value)
});
return Math.max.apply(this, numberValues);
Full demo, including using console.log rather than document.write , also including how to append to document without clearing it: http://jsfiddle.net/yYhjD/1/
<head>
<script type="text/javascript">
function compare() {
var elements = [].slice.call(document.getElementsByName('to_compare'));
var numberValues = elements.map(function(x){return Number(x.value)});
return Math.max.apply(this, numberValues);
}
</script>
</head>
<body>
<input type="text" id="value1" name="to_compare" value="-10"/>
<input type="text" id="value2" name="to_compare" value="080"/>
<input type="text" id="value3" name="to_compare" value="79"/>
<br/>
<input type="button" onclick="console.log(compare())" value="Compare!"/>
</body>
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