<script>
function doit(){
t = document.form_name.ta.scrollTop;
h = document.form_name.ta.scrollHeight;
c = document.form_name.ta.clientHeight;
if((h-t)<=c) document.form_name.bt.disabled = false;
}
</script>
<form name="form_name">
<textarea name="ta" rows="5" onscroll="doit()">
a
a
s
d
df
dsf
d
fdf
dsf
d
fd
</textarea>
<input type="button" name="bt" disabled="true" value="xxxxx">
</form>
function doit(){
t = document.form_name.ta.scrollTop;
h = document.form_name.ta.scrollHeight;
c = document.form_name.ta.clientHeight;
if((h-t)<=c) document.form_name.bt.disabled = false;
}
</script>
<form name="form_name">
<textarea name="ta" rows="5" onscroll="doit()">
a
a
s
d
df
dsf
d
fdf
dsf
d
fd
</textarea>
<input type="button" name="bt" disabled="true" value="xxxxx">
</form>
解决方案 »
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