js multiple select all and cancel all selection implementation code_javascript skills

Copy code The code is as follows:

$("select").change(function(){
var n = $(this).children().length;
var obj;
var i = 1;
$(this).children().each(function(){
if(i == n)
{
alert($(this).text());
}
i ;
});
});

Based on the above two methods, I easily got the effect I wanted, as follows:

Copy code The code is as follows:

function selectall()
{
$("select").children().each(function(){$(this).attr("selected" ,"selected")})
}

Used children() and $(this).attr("selected","selected") respectively
A js usage

Copy code The code is as follows:

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