Check a radio button with javascript

Question

For some reason, I can\'t seem to figure this out.

I have some radio buttons in my html which toggles categories:

Answer 1

Do not mix CSS/JQuery syntax (# for identifier) with native JS.

Native JS solution:

document.getElementById("_1234").checked = true;

JQuery solution:

$("#_1234").prop("checked", true);

Answer 2

I was able to select (check) a radio input button by using this Javascript code in Firefox 72, within a Web Extension option page to LOAD the value:

var reloadItem = browser.storage.sync.get('reload_mode');
reloadItem.then((response) => {
    if (response["reload_mode"] == "Periodic") {
        document.querySelector('input[name=reload_mode][value="Periodic"]').click();
    } else if (response["reload_mode"] == "Page Bottom") {
        document.querySelector('input[name=reload_mode][value="Page Bottom"]').click();
    } else {
        document.querySelector('input[name=reload_mode][value="Both"]').click();
    }
});

Where the associated code to SAVE the value was:

reload_mode: document.querySelector('input[name=reload_mode]:checked').value

Given HTML like the following:

    <input type="radio" id="periodic" name="reload_mode" value="Periodic">
    <label for="periodic">Periodic</label><br>
    <input type="radio" id="bottom" name="reload_mode" value="Page Bottom">
    <label for="bottom">Page Bottom</label><br>
    <input type="radio" id="both" name="reload_mode" value="Both">
    <label for="both">Both</label></br></br>

Answer 3

Easiest way would probably be with jQuery, as follows:

$(document).ready(function(){
  $("#_1234").attr("checked","checked");
})

This adds a new attribute "checked" (which in HTML does not need a value). Just remember to include the jQuery library:

<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.10.2/jquery.min.js"></script>

Answer 4

By using document.getElementById() function you don't have to pass # before element's id.

Code:

document.getElementById('_1234').checked = true;

Demo: JSFiddle

Answer 5

If you want to set the "1234" button, you need to use its "id":

document.getElementById("_1234").checked = true;

When you're using the browser API ("getElementById"), you don't use selector syntax; you just pass the actual "id" value you're looking for. You use selector syntax with jQuery or .querySelector() and .querySelectorAll().

Answer 6

Today, in the year 2016, it is save to use document.querySelector without knowing the ID (especially if you have more than 2 radio buttons):

document.querySelector("input[name=main-categories]:checked").value