Are you able to locate <td>s with identical classes using just a portion of the string?

Question

Are you able to locate <td>s with identical classes using just a portion of the string?

There are multiple classes in the <td>s of my table. I am looking to identify each <td> that contains a specific string.
For instance:

<table>
    <tr>
        <td class="hello there">foo</td>
        <td class="hello here">bar</td>
        <td class="not hello">baz</td>
    </tr>
</table>

I want to locate all td elements that contain the word "hello".
Is there a way to achieve this? Simply using className == will only return exact matches. That's a given.

javascript html-table

Answer 1

Answer №1

One way to target specific elements is by using the getElementsByClassName method:

document.getElementsByClassName('hello');

This code snippet will find all elements with the class name hello.

Note: The class attribute can contain multiple class names separated by spaces.

If you need compatibility with IE8 and older versions, you can achieve similar functionality like this:

var elements = document.getElementsByTagName("td"),
    helloElements = [],
    i = elements.length;

for (i--) {
    if ( ~(' ' + elements[i].className + ' ').indexOf(' hello ') ) {
        helloElements.push(elements[i]);
    }
}

Check out a working demo here: http://jsfiddle.net/AJEsp/

In response to @mplungjan's suggestion, here's a brief explanation of the bitwise tilde (~) trick:

The indexOf function returns the position of a substring within a string. For instance, 'abc'.indexOf('b') would return 1, and 'abc'.indexOf('c') would return 2. If the substring is not found, it returns -1.

The ~ character is one of the bitwise operators that inverts all bits. When applied to anything except -1, it results in a truthy value. Therefore, ~-1 becomes 0, indicating that the substring was found.

Hence, ~'str'.indexOf('substring') can be interpreted as a Boolean representing whether the substring was located in the string or not.

Answer 2

One way to target specific elements is by using the getElementsByClassName method:

document.getElementsByClassName('hello');

This code snippet will find all elements with the class name hello.

Note: The class attribute can contain multiple class names separated by spaces.

If you need compatibility with IE8 and older versions, you can achieve similar functionality like this:

var elements = document.getElementsByTagName("td"),
    helloElements = [],
    i = elements.length;

for (i--) {
    if ( ~(' ' + elements[i].className + ' ').indexOf(' hello ') ) {
        helloElements.push(elements[i]);
    }
}

Check out a working demo here: http://jsfiddle.net/AJEsp/

In response to @mplungjan's suggestion, here's a brief explanation of the bitwise tilde (~) trick:

The indexOf function returns the position of a substring within a string. For instance, 'abc'.indexOf('b') would return 1, and 'abc'.indexOf('c') would return 2. If the substring is not found, it returns -1.

The ~ character is one of the bitwise operators that inverts all bits. When applied to anything except -1, it results in a truthy value. Therefore, ~-1 becomes 0, indicating that the substring was found.

Hence, ~'str'.indexOf('substring') can be interpreted as a Boolean representing whether the substring was located in the string or not.

Answer 3

Answer №2

Consider implementing a solution similar to this:

var tds = document.getElementsByTagName("td");

for (var i = 0; i < tds.length; i++) {
    var cur = tds[i];
    var the_class = cur.className;
    if (the_class.split(" ").indexOf("hello") > -1) {
        // cur has the class "hello"
    }
}

There are alternative methods available as well.

You could utilize the .classList attribute, which is not fully supported yet - https://developer.mozilla.org/en-US/docs/DOM/element.classList.

Another option is using document.getElementsByClassName - https://developer.mozilla.org/en-US/docs/DOM/document.getElementsByClassName.

You can also explore document.querySelectorAll - https://developer.mozilla.org/en-US/docs/DOM/Document.querySelectorAll.

var td_with_class = document.querySelectorAll("td.hello");

Answer 4

Consider implementing a solution similar to this:

var tds = document.getElementsByTagName("td");

for (var i = 0; i < tds.length; i++) {
    var cur = tds[i];
    var the_class = cur.className;
    if (the_class.split(" ").indexOf("hello") > -1) {
        // cur has the class "hello"
    }
}

There are alternative methods available as well.

You could utilize the .classList attribute, which is not fully supported yet - https://developer.mozilla.org/en-US/docs/DOM/element.classList.

Another option is using document.getElementsByClassName - https://developer.mozilla.org/en-US/docs/DOM/document.getElementsByClassName.

You can also explore document.querySelectorAll - https://developer.mozilla.org/en-US/docs/DOM/Document.querySelectorAll.

var td_with_class = document.querySelectorAll("td.hello");

Answer 5

Answer №3

class="greetings friend" indicates that the td possesses two classes, greetings and friend.

Therefore, you can implement this code:

var items = document.getElementsByClassName('greetings');

Answer 6

class="greetings friend" indicates that the td possesses two classes, greetings and friend.

Therefore, you can implement this code:

var items = document.getElementsByClassName('greetings');

Answer 7

Answer №4

let tableCells = document.getElementsByTagName('td'),
    filteredCells = [];
for (let i = 0; i < tableCells.length; i++){
  if (tableCells[i].className.match(/\bhello\b/i)){
    filteredCells.push(tableCells[i]);
  }
}

Utilize the RegExp match function along with the \b symbol to target table cells with the specified class. Another approach is to filter in reverse, starting with the class name and then narrowing down by tagName:

let helloCells = document.getElementsByClassName('hello'),
    filteredCells = [];
for (let i = 0; i < helloCells.length; i++){
  if (helloCells[i].tagName == 'TD'){
    filteredCells.push(helloCells[i]);
  }
}

Answer 8

let tableCells = document.getElementsByTagName('td'),
    filteredCells = [];
for (let i = 0; i < tableCells.length; i++){
  if (tableCells[i].className.match(/\bhello\b/i)){
    filteredCells.push(tableCells[i]);
  }
}

Utilize the RegExp match function along with the \b symbol to target table cells with the specified class. Another approach is to filter in reverse, starting with the class name and then narrowing down by tagName:

let helloCells = document.getElementsByClassName('hello'),
    filteredCells = [];
for (let i = 0; i < helloCells.length; i++){
  if (helloCells[i].tagName == 'TD'){
    filteredCells.push(helloCells[i]);
  }
}

Answer 9

Answer №5

An effective approach is to retrieve all elements using their tag names ("td"). Then, loop through each element and check if the word "hello" is contained within the class attribute. Feel free to ask for the code snippet if you require it!

Answer 10

An effective approach is to retrieve all elements using their tag names ("td"). Then, loop through each element and check if the word "hello" is contained within the class attribute. Feel free to ask for the code snippet if you require it!

Answer 11

Answer №6

Surprisingly, jQuery's hasClass wasn't even mentioned by anyone.

Alternatively, you could simply use

var allHello = $("td.hello");

Answer 12

Surprisingly, jQuery's hasClass wasn't even mentioned by anyone.

Alternatively, you could simply use

var allHello = $("td.hello");

Answer 13

Answer №7

A useful property to check for classes is .classList.

elem.classList.contains( 'world' )

This line of code tells us if the element has the class "world" or not.

Check out this live example: http://jsfiddle.net/X9kLs/2/

.classList is widely supported in modern browsers, but doesn't work on older versions of IE (<10).

Answer 14

A useful property to check for classes is .classList.

elem.classList.contains( 'world' )

This line of code tells us if the element has the class "world" or not.

Check out this live example: http://jsfiddle.net/X9kLs/2/

.classList is widely supported in modern browsers, but doesn't work on older versions of IE (<10).

Answer 15

Answer №8

Retrieve all elements with both the 'blue' and 'example' classes
document.getElementsByClassName('blue example');

And to narrow it down to a specific element:

Locate all span elements with a class of 'example'

var examples = Array.prototype.filter( document.getElementsByClassName('example'), function(elem){
    return elem.nodeName == 'SPAN';
});

Answer 16

Retrieve all elements with both the 'blue' and 'example' classes
document.getElementsByClassName('blue example');

And to narrow it down to a specific element:

Locate all span elements with a class of 'example'

var examples = Array.prototype.filter( document.getElementsByClassName('example'), function(elem){
    return elem.nodeName == 'SPAN';
});

Are you able to locate <td>s with identical classes using just a portion of the string?

Answer №1

Answer №2

Answer №3

Answer №4

Answer №5

Answer №6

Answer №7

Answer №8

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