I'm trying to change all instances the word "blue" in a paragraph to another colour based on combo box input; the colour of the word changes to the corresponding input. Not sure what else to try. You can check my attached code.

document.querySelector(document).ready(function() {
  var button = document.querySelector("button_change");
  document.querySelector(button).click(function()

    {

      var select = document.querySelector("input_color").value;

      var element = document.querySelector(".cow_color");

      document.querySelector(element).html(inputValue);

    });
});

<h2>
  <span class="cow_color">Blue</span> Cow by Gelett Burgess (published in The Lark, 1895)
</h2>
<p>
  I never saw a <span class="cow_color">Blue</span> Cow, I never hope to see one; But I can tell you, anyhow, I'd rather see than be one.
</p>
<p>
  Change the cow's color to:
  <select id="input_color">
    <option value="Purple">Purple</option>
    <option value="Green">Green</option>
    <option value="Red">Red</option>
    <option value="Yellow">Yellow</option>
    <option value="Teal">Teal</option>
  </select>
  <button id="button_change">Change!</button>
</p>

<iframe name="sif1" sandbox="allow-forms allow-modals allow-scripts" frameborder="0"></iframe>

CodePudding user response：

1. You either need an eventListener or an onclick-trigger to run the script.
2. you use element.querySelectorAll('.class-name') as selector to select all classes with that class name
3. to apply the changes to all elements you use the .forEach(el => el.command) command.

final JS line should be:

document.querySelectorAll('.cow_color').forEach(el => elinnerHTML = document.querySelectorAll('#input_color').value;);

function changeColor() {
  var inputValue = document.querySelector('#input_color'),
      cowColor = document.querySelectorAll('.cow_color');
  
  cowColor.forEach(el => el.innerHTML = inputValue.value);
}

<h2>
  <span class="cow_color">Blue</span> Cow by Gelett Burgess (published in The Lark, 1895)
</h2>
<p>
  I never saw a <span class="cow_color">Blue</span> Cow, I never hope to see one; But I can tell you, anyhow, I'd rather see than be one.
</p>
<p>
  Change the cow's color to:
  <select id="input_color">
    <option value="Purple">Purple</option>
    <option value="Green">Green</option>
    <option value="Red">Red</option>
    <option value="Yellow">Yellow</option>
    <option value="Teal">Teal</option>
  </select>
  <button id="button_change" onclick="changeColor()">Change!</button>
</p>

<iframe name="sif2" sandbox="allow-forms allow-modals allow-scripts" frameborder="0"></iframe>

CodePudding user response：

Overview

Heres a jquery version

Example

Example

Explination:

we bind to the button, then on click event, we get the value from the dropdown selection. with that value we loop through all .cow_color and assign the color with the value we got previously and also it replaces the Text.

Code

$(document).on('click', '#button_change', (element) => {
  let color = $('#input_color').val();
  let spans = $('.cow_color');
  spans.map(function() {
    $(this).css('color', color);
    $(this).html(color);
  });
  return;
});

<!-- Jquery -->
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.5.1/jquery.min.js"></script>


<!-- Body -->
<h2>
  <span class="cow_color">Blue</span> Cow by Gelett Burgess (published in The Lark, 1895)
</h2>
<p>
  I never saw a <span class="cow_color">Blue</span> Cow, I never hope to see one; But I can tell you, anyhow, I'd rather see than be one.
</p>
<p>
  Change the cow's color to:
  <select id="input_color">
    <option value="Purple">Purple</option>
    <option value="Green">Green</option>
    <option value="Red">Red</option>
    <option value="Yellow">Yellow</option>
    <option value="Teal">Teal</option>
  </select>
  <button id="button_change">Change!</button>
</p>

<iframe name="sif3" sandbox="allow-forms allow-modals allow-scripts" frameborder="0"></iframe>