How to stop refreshing the select box option after pressing OK button - html

Question

I have created a UI Page in Servicenow below is my simple HTML snipped that creates a Select box and a OK button
Now i selected the select box as Mango and i typed ok, once i click on ok it is setting the value but when i refresh the browser it going to back to previous view. how to keep the same option which user select until user changes it
function validation(){
var value=document.getElementById("selectedValue").value;
if(value=='disabled selected')
{
alert("Please select any value before submitting");
}
else if(value=="1"){
alert("hello this is mango");
}
}
<div class="container">
<div class="row">
<div class="form-group" style="margin-top:12px;">
<select class="form-control" name="selectedValue" id="selectedValue" style="width:150px;">
<option value="disabled selected">Choose your option</option>
<option value="1" >Mango</option>
<option value="2">Orange</option>
<option value="3">Grapes</option>
</select>
<!--<h4 id="number_of_updates" style="display:none"><span class="label label-danger"></span></h4> -->
</div>
<button type="button" class="btn btn-primary" onclick="validation()" style="padding: 0px 8px;">Ok</button>
</div>
</div>
It is working as required, when i refresh the browser it will be set to Choose your option. Can anyone please help me how to save the selected value till it is changed

Answer 1

To achieve the desired result I would use localStorage.
I would set localStorage item inside your validation() function:
function validation(){
var value=document.getElementById("selectedValue").value;
localStorage.setItem('MyValue', value);
if(value=='disabled selected')
{
alert("Please select any value before submitting");
}
else if(value=="1"){
alert("hello this is mango");
}
}
Note, that I'm setting it to selected value from selectList.
Then we need to retrieve this saved value on page load(in case someone refreshes the page):
window.onload = function (){ //function that is called when your page
var selectList = document.getElementById('selectedValue');
var stored = localStorage.getItem('MyValue');
console.log(stored);
if(stored && selectList){
selectList.value = stored //setting saved value to as selected in selectList
}
}
EDIT: Even though localStorage is supported by majority of browsers, its is recommended to check if its accessible. Like if (typeof localStorage !== 'undefined') ...

Answer 2

There's several ways to keep state across refresh. localStorage is obvious choice but maybe an easier solution for your case may be encoding the state in the URL like this (basically the same way web apps keep some of their state).
Insert this code at the end inside validation() function:
history.pushState(null, '', '?val=' + value);
Insert this code after that function:
window.onload = function() {
var params = new URLSearchParams(location.search);
var value = params.get('val') || 'disabled selected';
var select = document.getElementById('selectedValue');
if (select) select.value = value;
}
That's it. Notes: URLSearchParams doesn't work on IE, instead it's not hard to parse the query by hand.