我怎样才能触发一个onchange function<selected> 元素></selected>

Question

I have a javascript function that needs to be triggered based on a selected option, however I would like for a default to be selected

<select class="custom-select" name="" id="timer1numbers" onchange="getSelected1()">
            <option value="4">4</option>
            <option value="5">5</option>
            <option value="6">6</option>
            <option value="7">7</option>
            <option value="8" selected>8</option>
            <option value="9">9</option>
            <option value="10">10</option>
        </select>
    </div>

How can I trigger the script without requiring a change from the user?

Answer 1

Just by calling document.getElementById("timer1numbers").onchange(); this, you can trigger your very first onchange event with the selected value.

Here is the code snippet and look at the console:

 function getSelected1() { var value = document.getElementById("timer1numbers").value; console.log(value); } document.getElementById("timer1numbers").onchange();

 <select class="custom-select" name="" id="timer1numbers" onchange="getSelected1()"> <option value="4">4</option> <option value="5">5</option> <option value="6">6</option> <option value="7">7</option> <option value="8" selected>8</option> <option value="9">9</option> <option value="10">10</option> </select>