Atomics.wait and Atomics.notify are low-level synchronization primitives useful for implementing mutexes and other means of synchronization. However, since Atomics.wait is blocking, it’s not possible to call it on the main thread (trying to do so throws a TypeError).
JavaScript supports a range of compound assignment operators that let programmers succinctly express a binary operation together with assignment. Currently, only mathematical or bitwise operations are supported.
JavaScript is now equipped with a new regular expression enhancement, called “match indices”. Imagine you want to find invalid variable names in JavaScript code that coincide with reserved words, and output a caret and an “underline” under the variable name, like:
If you’ve ever dealt with strings in JavaScript, chances are you came across the String#replace method. String.prototype.replace(searchValue, replacement) returns a string with some matches replaced, based on the parameters you specify:
Since the introduction of promises in ES2015, JavaScript has supported exactly two promise combinators: the static methods Promise.all and Promise.race.
Two new proposals are currently making their way through the standardization process: Promise.allSettled, and Promise.any. With those additions, there’ll be a total of four promise combinators in JavaScript, each enabling different use cases.