![]() ![]() The Memory tool opens in the bottom panel of DevTools.įrom the Detached Elements tool, select the Id field of a detached element. In the Detached Elements tool, click the Analyze ( ) icon. To identify the JavaScript code that references a detached element: The Analyze button takes a heap snapshot and populates the ID of the detached element with its location in the heap:įor more information about heap snapshots, read Record heap snapshots using the Memory tool. Once you have found a detached element that cannot be garbage-collected, you can use the Analyze button in the Detached Elements tool to identify the JavaScript code running on the page that is still referencing the detached element. Identify the JavaScript code that retains detached elements These detached elements may be memory leaks if they aren't going to be reused by the application. When you select Get Detached Elements, the Detached Elements tool displays all detached elements that cannot be garbage collected. When you select Collect garbage, the browser runs garbage collection. In the Detached Elements tool, click the Collect garbage ( ) icon.Ĭlick the Get Detached Elements ( ) icon. Next, trigger garbage collection (GC) in the browser: When you switch to Room 2 in the demo application, the messages that were generated in Room 1 are no longer attached to the DOM, but they are still referenced by JavaScript. The Detached Elements tool displays all of the detached elements of the page. In the Detached Elements tool, click the Get Detached Elements ( ) icon: In the demo application, click the Simulate high traffic button.Īfter some messages are generated and displayed in the demo application, click the demo's Stop button: In the demo application, make sure that the Room 1 button is selected. The Get Detached Elements ( ) button in the Detached Elements tool finds and displays all of the detached elements on a web page. ![]() If that tab isn't visible, click the More tabs ( ) button, or else the More Tools ( ) button: In DevTools, on the main toolbar, select the Detached Elements tab. Or, press Ctrl+Shift+I (Windows, Linux) or Command+Option+I (macOS). To open DevTools, right-click the webpage, and then select Inspect. Open the Detached Elements demo application in a new window or tab. To open the Detached Elements tool and load the demo page: The performance of a page is delayed or appears to pause frequently.The performance of a page is consistently bad.The performance of a page gets progressively worse over time.For the browser to garbage-collect (GC) the detached element, the element must not be referenced from the DOM tree or from JavaScript code.įor more information about heap snapshots and detached elements, read Discover detached DOM tree memory leaks with Heap Snapshots.Īs explained in Fix memory problems, memory issues affect page performance, including memory leaks, memory bloat, and frequent garbage collections. These elements are called detached elements. By changing your JavaScript to release the element, you reduce the number of detached elements on your page.Ī memory leak can occur in your application when an element is no longer attached to the Document Object Model (DOM) tree, but is still referenced by some JavaScript running on the page. A different Storage object is used for the sessionStorage and localStorage for each origin - they function and are controlled separately.Use the Detached Elements tool to find detached elements that the browser cannot garbage-collect, and locate the JavaScript object that is still referencing the detached element. These mechanisms are available via the ssionStorage and Window.localStorage properties (to be more precise, the Window object implements the WindowLocalStorage and WindowSessionStorage objects, which the localStorage and sessionStorage properties hang off) - invoking one of these will create an instance of the Storage object, through which data items can be set, retrieved and removed. Storage limit is the maximum amongst the two.Stores data with no expiration date, and gets cleared only through JavaScript, or clearing the Browser cache / Locally Stored Data.localStorage does the same thing, but persists even when the browser is closed and reopened.Storage limit is larger than a cookie (at most 5MB).Data is never transferred to the server.Stores data only for a session, meaning that the data is stored until the browser (or tab) is closed.sessionStorage maintains a separate storage area for each given origin that's available for the duration of the page session (as long as the browser is open, including page reloads and restores).The two mechanisms within Web Storage are as follows: ![]()
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