JSFiddle - React, Tailwind, and code Playground

HTML

<img src='http://placehold.it/50x50' id='img1' name='img1' />
<br/>
<select name="users" onchange="SwitchPic(img1);">
    <option value="">Select a Number:</option>
    <option value="a">a</option>
    <option value="b">b</option>
    <option value="c">c</option>
</select>

JavaScript

var clicked = false;

function SwitchPic(pic) {
    if (!clicked) {
        pic.src = "http://placehold.it/100x100";
        clicked = true;
    } else {
        pic.src = "http://placehold.it/50x50";
        clicked = false;
    }
}