js method to determine whether checkbox is selected_Basic knowledge

Core tip: On many occasions, you may encounter the problem of determining whether an element on the page is selected. The following is a method of using js to determine whether a CheckBox is selected.
//No number selected

Copy code The code is as follows:

< input type="checkbox" name="checkbox1" checked>
<input type="checkbox" name="checkbox1">
<input type="checkbox" name="checkbox1" checked>
<input type="checkbox" name="checkbox1">
<input type="checkbox" name="checkbox1">
<script language=javascript>
function check (obj)
{

for(i=0;i<document.all(obj).length;i )
{
if(!document.all(obj)[i ].checked)alert("No." (i 1) "No selection")
}
}
</script>
<input type=button onclick="check(' checkbox1')" value="Detection">

//No one selected

Copy code The code is as follows:

<input type="checkbox" name="test">
<input type="checkbox" name="test">
<input type="checkbox" name="test">
<input type="checkbox" name="test">
<input type="checkbox" name="test"> ;
<Script Language="JavaScript">
function check(obj){
for(i=0;i<document.all(obj).length;i ){
if (document.all(obj)(i).checked){
return;
}
}
window.alert('No one selected! ');
}
</Script>
<input type=button onclick="check('test');" value="Check">

//No number selected

Copy code The code is as follows:

<input type ="checkbox" name="checkbox1" checked>
<input type="checkbox" name="checkbox1">
<input type="checkbox" name="checkbox1" checked>
<input type="checkbox" name="checkbox1">
<input type="checkbox" name="checkbox1">
<script language=javascript>
function check(obj )
{

for(i=0;i<document.all(obj).length;i )
{
if(!document.all(obj)[i]. checked)alert("No." (i 1) "No selection")
}
}
</script>
<input type=button onclick="check('checkbox1' )" value="Detection">

//No one selected

Copy code The code is as follows:

<input type="checkbox" name="test">
<input type="checkbox" name="test">
< input type="checkbox" name="test">
<input type="checkbox" name="test">
<input type="checkbox" name="test">
<Script Language="JavaScript">
function check(obj){
for(i=0;i<document.all(obj).length;i ){
if(document .all(obj)(i).checked){
return;
}
}
window.alert('No one selected! ');
}
</Script>
<input type=button onclick="check('test');" value="Check">