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JavaScript Tutorials

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    React.isValidElement

    Knowing what input type you've received is hugely important in JavaScript, which is a big reason for Flow and TypeScript's rise. One such case where it's useful to know what an object represents is if the input is a string or a React element.To detect...

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    Detect Generator Functions with JavaScript

    In the current JavaScript climate of new syntaxes, features, and using loads of external libraries, it seems harder than ever to be sure what your functions are being given or even what the data represents. Of course, we've come up with Flow and TypeScript to help...

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    Node isConnected

    Every so often I discover a property in JavaScript objects that I didn't know existed, oftentimes using another trick to accomplish the same functionality. One such property I just learned about was isConnected, a node property that attached to a context (i.e. document).Here's how to...

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    Limit Promise Concurrency with pool

    Methods like Promise.all, Promise.allSettled, Promise.race, and the rest are really excellent for managing multiple Promises, allowing for our apps to embrace async and performance. There are times, however, that limiting the number of concurrent operations may be useful, like rate limiting or simply not wanting...

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    cookieStore: Async Cookie API

    One pattern in the JavaScript API world that web development veterans will notice is that we've been creating new methods to accomplish what older, grosser APIs once achieved. XMLHttpRequest became the fetch API, some APIs like Battery became async, and there are dozens of other examples.

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    How to Prevent Pasting into an Input

    Every once in a while I get to a website that doesn't allow me to paste into a form input. In most cases it's something to do with login credentials (username and or password) and auth codes. So how are they preventing me from...

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    How to Detect When a Sticky Element Gets Pinned

    The need for position: sticky was around for years before it was implemented natively, and I can boast that I implemented it with JavaScript and scroll events for ages. Eventually we got position: sticky, and it works well from a visual perspective, but I wondered how...

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    How to Create an Async Function via “new Function”

    One thing I love about JavaScript is that there are many ways to accomplish the same task, one such example being creating functions. There are several patterns for functions; one of the last you see used is the new Function method:What if you want...

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    5 Awesome JavaScript Promise Tricks

    The Promise API changed the game in JavaScript. We went from abusing setTimeouts and settling for synchronous operations to doing everything possible to leverage this new async API. Let's check out a handful of awesome Promise API tricks!Cancel a fetch RequestOne problem we...

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    Logical Assignment Operators

    I love JavaScript, it's my favorite programming language, but I love dipping into other languages because they offer a new perspective on coding paradigms. There've been syntax additions to JavaScript that I've seen I found interesting (think ?? in optional chaining) and...