Backbone js remove from collection8/9/2023 ![]() ![]() keys(), values(): get list of attribute names and values.omit(): extract all attributes from a model except those listed.pick(): extract a set of attributes from a model.groupBy(): group a collection into groups of like items.isEmpty(): determine whether a collection is empty.size(): return the size of a collection.any(): confirm if any of the values in a collection pass an iterator truth test.indexOf(): return the index of a particular item within a collection.log ( captions ) // will return a list of captions M圜ollection.reset() Underscore utility functionsīackbone takes full advantage of its hard dependency on Underscore by making many of its utilities directly available on collections: This is useful then dynamically loading a new page of results where you want to blank out the current page of results. Using reset with no arguments will clear out the collection completely. If we want to simply replace the entire content of the collection we can use Collection.reset(). The previous, document.getElementById, section detailed that the optional chaining operator is used here because app can potentially be null at runtime.Var myTodo = new Todo () The last line of the code snippet is app?.appendChild(p). In the code snippet, we use a property defined on the Node interface to append the new p element to the website. This prototypal extension allows for all HTMLElements to utilize a subset of standard methods. HTMLElement interface extends the Element interface which extends the Node interface. The document.getElementById function returns an HTMLElement. And if the code was document.createElement('a'), then it would be an element of type HTMLAnchorElement. This definition is how the p variable from the code snippet gets a type of HTMLParagraphElement. This is exactly what happens the return value HTMLElementTagNameMap takes the tagName argument and uses it to return the corresponding type. This means that the developer does not have to specify the generic parameter when using the method whatever value is passed to the tagName argument will be inferred as K and thus can be used throughout the remainder of the definition. The TypeScript interpreter is smart enough to infer the generic parameter from this argument. The first argument tagName is defined as the generic parameter K. Now, for the remainder of the createElement definition: (tagName: K, options?: ElementCreationOptions): HTMLElementTagNameMap. Some elements do not exhibit unique properties and so they just return HTMLElement, but other types do have unique properties and methods so they return their specific interface (which will extend from or implement HTMLElement). For example here are the first 5 mapped values: The map interface contains every specified HTML tag name and its corresponding type interface. This expression defines a generic parameter K that is constrained to the keys of the interface HTMLElementTagNameMap. It is best understood broken down into chunks, starting with the generic expression. This definition is what enables developers to create unique HTML element tags.įor example document.createElement('xyz') returns a element, clearly not an element that is specified by the HTML specification.įor those interested, you can interact with custom tag elements using the document.getElementsByTagNameįor the first definition of createElement, it is using some advanced generic patterns. ![]() Pass it any string and it will return a standard HTMLElement. The second overload is simplest and works a lot like the getElementById method does. This is an overloaded function definition. You can explore the source code for the DOM type definitions Basic ExampleĬreateElement ( tagName : string, options ?: ElementCreationOptions ): HTMLElement This type is the backbone for DOM manipulation with TypeScript. Of the 20,000+ lines of definitions in .ts, one stands out among the rest: HTMLElement. These definitions are readily available in any default TypeScript project. TypeScript is a typed superset of JavaScript, and it ships type definitions for the DOM API. The API is so powerful that countless frontend frameworks (jQuery, React, Angular, etc.) have been developed around it to make dynamic websites even easier to develop. The DOM API can be used to change the document structure, style, and content. The Document Object Model (DOM) is a programming interface implemented by browsers to make static websites functional. These documents are static, they do not change. Websites are made up of HTML and/or XML documents. While in 2020, JavaScript can be used on servers, in data science, and even on IoT devices, it is important to remember its most popular use case: web browsers. In the 20+ years since its standardization, JavaScript has come a very long way. DOM Manipulation An exploration into the HTMLElement type ![]()
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