add default value to select html code example
Example 1: html select default
<select>
<option value="" selected disabled hidden>Choose here</option>
<option value="1">One</option>
<option value="2">Two</option>
<option value="3">Three</option>
<option value="4">Four</option>
<option value="5">Five</option>
</select>
Example 2: html initialize select
//html
//<select name="sel" id="sel></select>
//js
//generating options
let sel = document.getElementbyID('sel');
let opt = ['option1', 'option2', 'option3'];
for(let idx=0; idx<opt.length; idx++){
sel.options[idx] = new Option(opt[idx], opt[idx]); //new Option("Text", "Value")
}
//init
for(let idx=0; idx<sel.length; idx++){
sel.options[idx] = undefined;
}
//generating other options
let opt2 = ['optA', 'optB', 'optC'];
for(let idx=0; idx<opt2.length; idx++){
sel.options[idx] = new Option(opt2[idx], opt2[idx]);
}