Uncaught TypeError: Cannot read property ‘value’ of undefined

Code (text):

function deleterow(id){

    document.form1.elements[‘del[]‘][id].value = 1

    count_del_price()

    document.getElementById("tr"+id).style.display = ‘none’

}

function count_del_price(){

    priceminus = 0;

    inputCount = document.form1.elements[‘del[]‘].length //document.form1.elements[‘tcounter’].value

    for(i=0; i<=inputCount; i++){

        if(document.form1.elements[‘del[]‘][i].value == 1){// Uncaught TypeError: Cannot read property ‘value’ of undefined

            priceminus +=…

Uncaught TypeError: Cannot read property 'value' of undefined

See original post by greatlogix