How to check element existence using its alias attributes with Mootools

How to check element existence using its alias attributes with Mootools

Tried as follows. But its not working,

<select alias="school_type" id="15_4_19" name="15_4_19">
    <option label="" value="">Select</option>
    <op开发者_StackOverflow中文版tion selected="selected" label="High School" value="8">High School</option>
    <option label="University" value="9">University</option>
    <option label="Elementary Schools" value="10">Elementary Schools</option>
</select>


if($$('select[alias=school_type]'))
{
    var elv = $$('select[alias=school_type]');
    var schoolType = elv[0].id;

    data['type_id'] = $(schoolType).get('value');
}

Any help please

$$ was sort of an alias for document.getElements (or Slick.find now) and will always return a HTML collection--even when with 0 members. hence, the if ($$()) assertion will not be falsy.

either do if ($$('selector').length) or if (document.getElement('select[alias=foo]')) instead, which will be null or element object so will evaluate falsy

Rewrite this to:

var selectEl = document.getElement('select[alias=school_type]');
if (selectEl) {
    data['type_id'] = selectEl.get('value');
}