CODEWITHSUNDEEP
javascript
narfie
narfie

Reputation: 493

Select elements by Input Type and apply CSS classes based on values

I have a page that contains a whole bunch of input boxes of type number. These can be individually changed, or a set of them can be changed by a selector.

I would like to show the user which input boxes have values greater than 0 in them by changing the class of the input box.

I cannot use JQuery. It has to be done with pure Javascript.

I understand I will need to use an event listener to attach a function to it?

Anyway... here's a piece of html as an example:

<input name="qty1" type="number" min="0" value="0">
<input name="qty2" type="number" min="0" value="0">
<input name="qty3" type="number" min="0" value="0">
<input name="qty4" type="number" min="0" value="0">
<input name="qty5" type="number" min="0" value="0">

Here's some Javascript I think should go with this:

function changeInputClass(element){
  if(element.value > 0){
    //add class 'bold-text' to this element
  }
  else {
    //remove class 'bold-text' from this element
  }
}

var myElements = document.getElementsByTagName('input');
for(var i=0; i<myElements.length; i++){
  if(myElements[i].type == 'number') {
    // add event listener here to call function changeInputClass()
  }
}

Appreciate the help.

Update of more realistic representation of the html:

<div id="selections" class="selections">
  <div class="images-container">
    <div>
      <div class="image-options">
        <div class="product-option">
          <div class="qty"><input name="qty1" type="number" min="0" value="0"></div>
          <div>Product Description 1</div>
        </div>
        <div class="product-option">
          <div class="qty"><input name="qty2" type="number" min="0" value="0"></div>
          <div >Product Description 2</div>
        </div>
        <div class="product-option">
          <div class="qty"><input name="qty3" type="number" min="0" value="0"></div>
          <div >Product Description 3</div>
        </div>
      </div>
      <div class="image-options">
        <div class="product-option">
          <div class="qty"><input name="qty4" type="number" min="0" value="0"></div>
          <div >Product Description 4</div>
        </div>
        <div class="product-option">
          <div class="qty"><input name="qty5" type="number" min="0" value="0"></div>
          <div >Product Description 5</div>
        </div>
        <div class="product-option">
          <div class="qty"><input name="qty6" type="number" min="0" value="0"></div>
          <div >Product Description 6</div>
        </div>
      </div>
    </div>
  </div>
</div>

Created a fiddle http://jsfiddle.net/narfie/g3gbqaxz/14/

Upvotes: 0

Views: 736

Answers (4)

bluefog
bluefog

Reputation: 1894

Now I made an array of all the input elements by going through the first child of the element with class qty. Made a single function to check changes to that element array. Added the onchange to any higher ancestor of the input element.

var inputs = new Array();
window.onload = function () {
    var qtys = document.getElementsByClassName("qty");
    for (var i = qtys.length - 1; i >= 0; i--) {
        inputs[i] = qtys[i].children[0];
    };
}
function check() {
    for (var i = inputs.length - 1; i >= 0; i--) {
        if(inputs[i].value>0){
            inputs[i].classList.add("has-value");
        }
        else{
            inputs[i].classList.remove("has-value");
        }
    };
}

Rest at fiddle : http://jsfiddle.net/1jcyhpyL/8/

Upvotes: 1

Xotic750
Xotic750

Reputation: 23492

Here is an example of using modern methods that handle most situations. You still have the problem where a value is changed programatically (even mutation observers do not handle this), as described by @RobG. But this should give a fair demonstration of the common situations.

function changeClass(e) {
    var target = e.target || e;

    if (target.nodeName === 'INPUT' && target.type === 'number') {
        if (target.valueAsNumber > 0) {
            target.classList.remove('noValue');
            target.classList.add('hasValue');
        } else {
            target.classList.add('noValue');
            target.classList.remove('hasValue');
        }
    }
}

[].forEach.call(document.querySelectorAll('input[type="number"]'), changeClass);

new MutationObserver(function (mutations) {
    mutations.forEach(function (mutation) {
        if (mutation.type === 'childList') {
            [].forEach.call(mutation.addedNodes, changeClass);
        }
    });
}).observe(document, {
    attributes: false,
    attributeOldValue: false,
    characterData: false,
    characterDataOldValue: false,
    childList: true,
    subtree: true
});

document.addEventListener('change', changeClass, false);

document.querySelector('[name="qty5"]').value = 1;

var newinput = document.createElement('input');

newinput.name = 'qty6';
newinput.type = 'number';
newinput.min = 0;
newinput.value = 1;

document.body.appendChild(newinput);

var qty4 = document.querySelector('[name="qty4"]');

qty4.value = 1;
changeClass(qty4);
.noValue {
    background: red;
}
.hasValue {
    background: yellow;
}
<input name="qty1" class="noValue" type="number" min="0" value="0">
<input name="qty2" class="noValue" type="number" min="0" value="0">
<input name="qty3" class="noValue" type="number" min="0" value="0">
<input name="qty4" class="noValue" type="number" min="0" value="0">
<input name="qty5" class="noValue" type="number" min="0" value="0">

Upvotes: 0

RobG
RobG

Reputation: 147453

I have a page that contains a whole bunch of input boxes of type number. These can be individually changed

For that you can use a change listener on each element. You could delegate to an ancestor, but the change event doesn't bubble in all browsers.

or a set of them can be changed by a selector.

If you change values by script, that will not cause a change event to be dispatched, so you can either manually call the listener, or dispatch your own change event (and make it bubble).

In modern browsers (probably IE 9+) you can do:

function changeInputClass(){
  [].forEach.call(document.querySelectorAll('input[name^=qty]'), function(element) {
    if (element.value > 0) {
      element.classList.add('bold-text');
    } else {
      element.classList.remove('bold-text');
    } 
  });
}

In less modern browsers (even IE 6) you can do:

function changeInputClass(){
  var node, nodes = document.getElementsByTagName('input');
  var nameRE = /^qty/;

  for (var i=0, iLen=nodes.length; i<iLen; i++) {
    node = nodes[i];

    if (nameRE.test(node.name)) {
      if (node.value > 0) {
        node.className = 'bold-text';
      } else {
        node.className = '';
      }
    }
  }
}

Upvotes: 0

webtrick101
webtrick101

Reputation: 214

<html>
<body>

<input name="qty1" type="number" min="0" value="0" onchange="changeInputClass(this)">
<input name="qty2" type="number" min="0" value="0" onchange="changeInputClass(this)">
<input name="qty3" type="number" min="0" value="0" onchange="changeInputClass(this)">
<input name="qty4" type="number" min="0" value="0" onchange="changeInputClass(this)">
<input name="qty5" type="number" min="0" value="0" onchange="changeInputClass(this)">

<script>
function changeInputClass(element) {

 if (element.value > 0){
  element.style.fontWeight = 'bold';    
 }
 else {
  element.style.fontWeight = 'normal';  
 }
}
</script>


</body>
</html>

Upvotes: 0

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