Glossary Index
Explore the glossary map
Open a larger visual map of glossary categories and related terms without adding weight to the initial index load.
View glossary map
Hide glossary map
Showing 1–50 of 146 terms.
R
146 terms
The r CSS property defines the radius of a circle.
RAIL, an acronym for Response, Animation, Idle, and Load, is a performance model originated by the Google Chrome team in 2015, focused on user experience and performance within the browser.
Warning: This method parses its input as HTML or XML, writing the result into a DocumentFragment that might subsequently be injected into the DOM.
The Range.getBoundingClientRect() method returns a DOMRect object that bounds the contents of the range; this is a rectangle enclosing the union of the bounding rectangles for all the elements in the range.
The Range.selectNodeContents() method sets the Range to contain the contents of a Node.
The RangeError object indicates an error when a value is not in the set or range of allowed values.
A raster image is an image file defined as a grid of pixels.
In computing, especially in networking, rate limiting means controlling how many operations can be performed in a given amount of time, usually to avoid overloading the system and causing performance degradation.
rawurlencode() — URL-encode according to RFC 3986.
A concurrency technique that publishes replacement data and defers old-data reclamation until existing readers finish.
A cache that retrieves missing entries through its own configured data loader.
Additional storage or lookup work performed to satisfy a logical application read.
Reading order refers to the order in which content is accessed, for example when read out by a screen reader, or navigated to using sequential navigation methods such as tabbing through links or buttons.
An anomaly in which related reads reflect incompatible database states and produce an inconsistent combined view.
A session guarantee that later reads can observe that client's own completed writes.
realpath() — Returns canonicalized absolute pathname.
Real User Monitoring (RUM) measures the performance of a page from real users' machines.
recurse_dirsize(): Gets the size of a directory recursively.
The act of a function calling itself, recursion is used to solve problems that contain smaller sub-problems.
Redis is an in-memory data store that supports structured values, expiration, and server-side operations.
A Redis object cache connects WordPress's object-cache API to Redis so selected cached values can persist between requests.
The ReferenceError object represents an error when a variable that doesn't exist (or hasn't yet been initialized) in the current scope is referenced.
The Reflect namespace object contains static methods for invoking interceptable JavaScript object internal methods.
The Reflect.apply() static method calls a target function with arguments as specified.
The Reflect.construct() static method is like the new operator, but as a function.
The Reflect.defineProperty() static method is like Object.defineProperty() but returns a Boolean.
The Reflect.deleteProperty() static method is like the delete operator, but as a function.
The Reflect.get() static method is like the property accessor syntax, but as a function.
The Reflect.getOwnPropertyDescriptor() static method is like Object.getOwnPropertyDescriptor().
The Reflect.getPrototypeOf() static method is like Object.getPrototypeOf().
The Reflect.has() static method is like the in operator, but as a function.
The Reflect.isExtensible() static method is like Object.isExtensible().
The Reflect.ownKeys() static method returns an array of the target object's own property keys.
The Reflect.preventExtensions() static method is like Object.preventExtensions().
The Reflect.set() static method is like the property accessor and assignment syntax, but as a function.
The Reflect.setPrototypeOf() static method is like Object.setPrototypeOf() but returns a Boolean.
Reflow happens when a browser recalculates the position and geometry of certain parts of a webpage, such as after an update on an interactive site.
A cache that refreshes eligible entries before expiry to reduce misses seen by readers.
The RegExp object is used for matching text with a pattern.
For an introduction to regular expressions, read the Regular Expressions chapter in the JavaScript Guide.
The RegExp.escape() static method escapes any potential regex syntax characters in a string, and returns a new string that can be safely used as a literal pattern for the RegExp() constructor.
The dotAll accessor property of RegExp instances returns whether or not the s flag is used with this regular expression.
The exec() method of RegExp instances executes a search with this regular expression for a match in a specified string and returns a result array, or null.
The flags accessor property of RegExp instances returns the flags of this regular expression.
The global accessor property of RegExp instances returns whether or not the g flag is used with this regular expression.
The hasIndices accessor property of RegExp instances returns whether or not the d flag is used with this regular expression.
The ignoreCase accessor property of RegExp instances returns whether or not the i flag is used with this regular expression.
The multiline accessor property of RegExp instances returns whether or not the m flag is used with this regular expression.
The source accessor property of RegExp instances returns a string containing the source text of this regular expression, without the two forward slashes on both sides or any flags.
The sticky accessor property of RegExp instances returns whether or not the y flag is used with this regular expression.