Results 1 - 20 of 1,033

<element>

The HTML <element> element is used to define new custom DOM elements.
Element HTML NeedsContent Reference Web Web Components

<template>

The HTML template element <template> is a mechanism for holding client-side content that is not to be rendered when a page is loaded but may subsequently be instantiated during runtime using JavaScript. 
Element HTML Reference Web Web Components

actual value

The actual value of a CSS property is the used value after all approximations have been applied. For example, a user agent may only be able to render borders with a integer pixel value and may be forced to approximate the computed width of the border.
CSS Guide Web

Common CSS questions

Browsers use the DOCTYPE declaration to choose whether to show the document using a mode that is more compatible  with Web standards or with old browser bugs. Using a correct and modern DOCTYPE declaration at the start of your HTML will improve browser standards compliance.
CSS Example Guide Web

Computed value

The computed value of a CSS property is computed from the specified value by:
CSS Guide Web

inheritance

The summary of every CSS property definition says whether that property is inherited by default ("Inherited: Yes") or not inherited by default ("Inherited: no"). This controls what happens when no value is specified for a property on an element.
CSS Guide Web

initial value

The initial value given in the summary of the definition of each CSS property has different meaning for inherited and non-inherited properties.
CSS Guide Web

Shorthand properties

Shorthand properties are CSS properties that let you set the values of several other CSS properties simultaneously. Using a shorthand property, a Web developer can write more concise and often more readable style sheets, saving time and energy.
CSS Guide Web

Used value

The used value of any CSS property is the final value of that property after all calculations have been performed. For some properties, used values can be retrieved by calling window.getComputedStyle. Dimensions (e.g., width, line-height) are all in pixels, shorthand properties (e.g., background) are consistent with their component properties (e.g., background-colordisplay) and consistent with position and float, and every CSS property has a value.
CSS Guide Web

Frame Timing API

The PerformanceFrameTiming interface provides frame timing data about the browser's event loop. A frame represents the amount of work a browser does in one event loop iteration such as processing DOM events, resizing, scrolling, rendering, CSS animations, etc. A frame rate of 60 fps (frames per second) for a 60 Hz refresh rate is a common target for a good responsive user experience. This means the browser should process a frame in about 16.7 ms.
Guide Overview Web Performance

Using the Frame Timing API

The PerformanceFrameTiming interface provides frame timing data about the browser's event loop. A frame represents the amount of work a browser does in one event loop iteration such as processing DOM events, resizing, scrolling, rendering, CSS animations, etc. A frame rate of 60 fps (frames per second) for a 60 Hz refresh rate is a common target for a good responsive user experience. This means the browser should process a frame in about 16.7ms.
Guide Web Performance

Navigation Timing API

The Navigation Timing API provides data that can be used to measure the performance of a website. Unlike other JavaScript-based mechanisms that have been used for the same purpose, this API can provide end-to-end latency data that can be more useful and accurate.
API Performance performance Web

Performance Timeline

The Performance Timeline API defines extensions to the Performance interface to support client-side latency measurements within applications. The extensions provide interfaces to retrieve performance entry metrics based on specific filter criteria. The standard also includes interfaces that allow an application to define performance observer callbacks that are notified when specific performance events are added to the browser's performance timeline.
Guide Overview Web Performance

Using Performance Timeline

The Performance Timeline standard defines extensions to the Performance interface to support client-side latency measurements within applications. The standard also includes interfaces that allow an application to be notified when specific performance events occur. Together, these interfaces can be used to help identify an application's performance bottlenecks.
Guide Web Performance

Resource Timing API

The Resource Timing interfaces enable retrieving and analyzing detailed network timing data regarding the loading of an application's resource(s). An application can use the timing metrics to determine, for example, the length of time it takes to load a specific resource, such as an XMLHttpRequest, <SVG>, image, or script.
Guide Overview Web Performance

Using the Resource Timing API

The Resource Timing interfaces enable retrieving and analyzing detailed network timing data regarding the loading of an application's resource(s). An application can use the timing metrics to determine, for example, the length of time it takes to fetch a specific resource such as an XMLHttpRequest, <SVG>, image, script, etc.).
Guide Web Performance

Functions and classes available to Web Workers

In addition to the standard JavaScript set of functions (such as String, Array, Object, JSON etc), there are a variety of functions available from the DOM to workers. This article provides a list of those.
Reference Référence Web