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A focused thread through the archive.
Arrow functions are compact JavaScript functions with a few deliberate differences from ordinary functions. They are excellent for small transformations and callbacks. They are not a universal replacement for function, …
JavaScript’s this is not difficult because it does many things. It is difficult because one small word changes value based on how a function is called. That makes this look unpredictable when the real problem is …
Closures show up any time a JavaScript function uses a variable defined from outside its own curly braces. That makes them common in callbacks, event handlers, timers, factory functions, and plenty of code that passes …
Hoisting is JavaScript’s setup behavior for declarations. It affects whether a function or variable can be used before the line where it appears in the file. That matters because function, var, let, and const do …
Most JavaScript code starts with a simple act: you give a value a name. We call that a variable declaration. That sounds small, but the way you create that name affects how the rest of your code can use it. A variable …
A Promise is a guaranteed placeholder value for what a function or series of functions will return. It’s a promise to return a value eventually. The function swears this time is different. You can trust it. It …
JavaScript’s spread syntax, ..., lets you expand one value into another context. It is small, useful, and easy to misunderstand. The practical version is this: In an array literal, spread adds values from an …
Brief History of Callbacks It all starts with the callback function. A callback function is just a plain JavaScript function that is passed into another function as an argument. That’s it. Nothing special. This …
JavaScript Function Signatures Alright, you’ve probably seen functions before. Something like this maybe? function doSomething(name, desc, task) { // did something } This function, named doSomething, takes three …
