Use cases of Observeation API

Syntax

// Create observer API instanceobserver=new MutationObserver( intersectionCallback, config );// Define intersectionCallback() function to // do operations when mutation happens.function intersectionCallback( entries, observer )// Call observe() method to observe the target HTML element.observer.observe( targetElement );...

Benefits of Observer API

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Use cases of Observeation API

Mutation observers work asynchronously, so they don’t block the main thread of JavaScript and keep the website responsive/performing for user interactions. This API provides information about the mutated elements that helps us to observe the element in an efficient manner. Observing multiple elements parallelly is possible with the help of this API so it makes the code clean and more useful for larger applications. Event listener’s callback functions are triggered when an event occurs, so their triggering depends on the occurrence of events, but in the case of mutation observer, we can detect changes without the occurrence of events. Different types of mutations of the same element or of different elements can be detected at the same time. This can’t be possible without the help of other methods....

Instance Methods

Detect the presence of specific elements (e.g.; add banners ) and take action if they are removed by ad blockers. detect any type of DOM modifications Used to implement auto-save functionality in online code editors (e.g.’; Leetcode, Hackerrank, GFG, etc). Detect UI updates of multiple elements on real real-time basis. Monitor input field for changes and validate user input in real-time, showing them error messages and feedback if required. Besides the above-mentioned use cases, limitless new functionalities can be implemented with the help of mutation observers....

Detecting style change in target HTML element

MutationCallback Function: It is the callback function that is called automatically when a mutation of the target elements happens. It receives 2 parameters: first is a list of all the MutationObserverEntry objects of all the targeted elements that are to be observed. The MutationObserverEntry object has multiple properties to check whether mutations happened or not. Config: It tells the observer what we want to observe. The following options can be provided within the config parameter. childList:true -> This parameter is used to observe changes in the target or target’s direct children only. If True is set, then the callback function be triggered when nodes are added, updated or removed from the target or its direct children only. subtree: true -> used to detect changes in the entire subtree of the target element. attributes: true -> used to detect changes in the target element’s specified attributes. attributeFilter: [array of attributes] -> used to observe mutation only when the specified attributes of the target element change. characterData: true -> used to observe mutations in textContent, innerHTML, innerText, or nodeValue of the target element. observe() method: when the observe method is invoked, mutation observer API starts monitoring mutations of the target element. entries: It is an array of MutationObserverEntry objects maintained by observer API for each targeted element. MutationObserverEntry object holds useful information about all of the targeted elements whether they are mutating or not....

Observe Input changes in the Given Paragraph

We have a single