In this article, we’ll look at the most reliable ways to manipulate the DOM.
Use Newer DOM Manipulating Methods
document object has the
querySelectorAll methods, which are more versatile than the old
querySelector returns the first element that has the given CSS selector.
querySelectorAll returns a NodeList of all the elements that have the given CSS selector.
For instance, given the following HTML code:
<p> foo </p> <p> bar </p> <p> baz </p>
Then we can get the first p element with the
document.querySelector method as follows:
const p = document.querySelector('p');
If we want to get all the p elements, we can write the following code:
const p = document.querySelectorAll('p');
NodeLists are array-like iterable objects, so we should convert them to an array with the spread operator so that we can manipulate the list more easily:
const ps = document.querySelectorAll('p'); const arr = [...ps];
Once we converted the NodeList to an array, we can use any array methods with it that we wish to.
For instance, we can get the p element with the content ‘bar’ as follows:
const ps = document.querySelectorAll('p'); const arr = [...ps]; const bar = arr.find(a => a.innerText === 'bar');
bar has the p element with the
innerText value set to
If we use
querySelector , then if the given element isn’t found, it’ll return
null . Therefore, we should make sure that we check for that before doing anything.
For instance, if we have the HTML above, and we have the following code:
const div = document.querySelector('div');
div will be
Therefore, we should make sure to check for
null to prevent possible crashes arising from attempting to manipulate
Displaying Things with InnerHTML
innerHTML property of an element object lets us set the HTML content of an element. It lets us add child elements to the DOM without using
appendChild as the browser will automatically put the items into the DOM tree.
For instance, given the following HTML:
<p> foo </p>
Then we can add bold text with the b tag as follows:
const p = document.querySelector('p'); p.innerHTML = '<b>foo</b>';
Then we’ll see that text ‘foo’ is bold.
Checking for DOM Elements with the hasAttribute Method
DOM elements has the
hasAttribute method to check if an element has an attribute. This is useful for checking if an element has the given attribute before doing anything.
For instance, we can write the following code to check if an attribute exists in a given element:
<p class='foo'> foo </p>
Then we can check if the
class attribute is in the p element by writing:
const p = document.querySelector('p'); const hasClass = p.hasAttribute('class');
class attribute exists in the p tag, then
hasClass should be
true . If the attribute doesn’t exist in the element, then
Getting All Attributes of an Element with the DOM Node Object’s attributes Property
A DOM element has an
attributes property that returns an array-like iterable object that has all the properties of the given element in the object.
For instance, if we have the following HTML:
<p class='foo'> foo </p>
Then we can get the attributes of the p tag as follows:
const p = document.querySelector('p'); const attributes = [...p.attributes];
attributes is an array with the attributes as entries. Notice that we used the spread operator to convert the array-like object to an array.
Each entry has properties for the name and value of the attribute. It also has properties like the child elements and text content for the attribute values.
The best way to get one or more elements is to use the
document.querySelectorAll methods respectively.
If we use
querySelectorAll to get all elements with the given selector, then we should convert the returned NodeList to an array with the spread operator so that manipulation of the items will be easier.
If we use the
querySelector method, then it returns
null if no entries with the given selector are found, so we should check for that.
To check if an attribute exists in a DOM element, then we should get a DOM element with the
hasAttribute method. It returns a boolean indicating if the attribute exists in a DOM element.
To get all the attributes of an element, we can use the
attributes property of an element object. It returns an array-like iterable object, so we should again use the spread operator to spread it into an array.