Данная функция делает поле динамически обязательным или рекомендуемым. Скопируйте функцию в событие OnLoad и вызовите как указано в комментариях в примере:

//****************************************************
gSetFieldRequired = function (field, src, height, width){

/*
Description: This function is used to dynamically make a field required, recommended in JavaScript
Params:    field  = name of the field
src  = url with image eg. /_imgs/frm_required.gif
height =  number, optional e.g. 50
width  =  number optional e.g. 50
Returns:   nothing
Example 1 :  gSetFieldRequired(, 'new_partweight', 'required');     = add *-sign to label
Example 2:   gSetFieldRequired( 'new_partweight', 'recommended');     = add +-sign to label
Example 3:   gSetFieldRequired(, 'new_partweight', 'none');      = no image
Calls:    nothing
Author:  Geron Profet
*/

var attribute = document.getElementById(field);
if (!attribute){return};

switch(src.toLowerCase())
{
case 'required':
src = '/_imgs/frm_required.gif';
attribute.setAttribute('req', 2);
break;
case 'recommended':
src = '/_imgs/frm_recommended.gif';
attribute.setAttribute('req', 1);
break;
case 'none':
src = ''
attribute.setAttribute('req', 0);
break;
}

//if src is passed add image
if (src != '') {
var img = document.createElement("img");
img.setAttribute('src', src);

//check if custom height and width
if (height && height != '' ){img.setAttribute('height', height);}
if (width && width != '' ){img.setAttribute('height', width);}
//img.setAttribute('width', width);

var objLabel = document.getElementById(field+'_c');
if (objLabel){objLabel.appendChild(img)};
}
else{
document.getElementById(field+'_c').innerHTML = document.getElementById(field+'_c').innerText;
}
}

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