Question

Can anyone work out why this does not work. Produces NAN and if reset for a Number(document on var inputs produces 0. The script is supposed to add up an indefinite number of fields starting with an ID of product_total_price_PRI_ … .

Obviously I’ve missed something and have got a headache from trying to see it.

function getFields() {
    var inputs = document.getElementsByTagName('input');
    var result = 0;
    for( var i = 0; i < inputs.length; i++ ) {
        if( inputs[i].id.indexOf('product_total_price_PRI_') == 0 );
           result += parseFloat(inputs[i].value); 
     }

    alert(result);
}

Answer 1

Your if() syntax is off, there’s a ; ending the statement so your result += is always running, it should be:

function getFields() {
    var inputs = document.getElementsByTagName('input');
    var result = 0;
    for( var i = 0; i < inputs.length; i++ ) {
        if( inputs[i].id.indexOf('product_total_price_PRI_') == 0 ) //no ; here
           result += parseFloat(inputs[i].value); 
     }

    alert(result);
}