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Sep 8, 2023 · Promises are a powerful tool in JavaScript that help manage asynchronous operations and provide a more readable and maintainable codebase. In this tutorial, we will take you from a beginner's level to an expert level, covering all the important aspects of JavaScript promises.
- Shrihari
Jun 23, 2024 · A promise is a special JavaScript object that links the “producing code” and the “consuming code” together. In terms of our analogy: this is the “subscription list”.
In this book, you'll learn all of the ins and outs of promises, from basics such as how to create promises all the way to understanding how async functions work with promises behind-the-scenes.
- Summary of The Handbook
- A Little Bit of History
- Just Javascript
- A Brief Intro to The Syntax of Javascript
- Semicolons
- Values
- Variables
- Types
- Expressions
- Operators
Created in 1995, JavaScript has gone a very long way since its humble beginnings. It was the first scripting language that was supported natively by web browsers, and thanks to this it gained a competitive advantage over any other language and today it's still the only scripting language that we can use to build Web Applications. Other languages ex...
Sometimes it's hard to separate JavaScript from the features of the environment it is used in. For example, the console.log()line you can find in many code examples is not JavaScript. Instead, it's part of the vast library of APIs provided to us in the browser. In the same way, on the server it can be sometimes hard to separate the JavaScript langu...
In this little introduction I want to tell you about 5 concepts: 1. white space 2. case sensitivity 3. literals 4. identifiers 5. comments
Every line in a JavaScript program is optionally terminated using semicolons. I said optionally, because the JavaScript interpreter is smart enough to introduce semicolons for you. In most cases, you can omit semicolons altogether from your programs without even thinking about it. This fact is very controversial. Some developers will always use sem...
A hello string is a value. A number like 12 is a value. hello and 12 are values. string and number are the typesof those values. The typeis the kind of value, its category. We have many different types in JavaScript, and we'll talk about them in detail later on. Each type has its own characteristics. When we need to have a reference to a value, we ...
A variable is a value assigned to an identifier, so you can reference and use it later in the program. This is because JavaScript is loosely typed, a concept you'll frequently hear about. A variable must be declared before you can use it. We have 2 main ways to declare variables. The first is to use const: The second way is to use let: What's the d...
Variables in JavaScript do not have any type attached. They are untyped. Once you assign a value with some type to a variable, you can later reassign the variable to host a value of any other type without any issues. In JavaScript we have 2 main kinds of types: primitive types and object types.
An expression is a single unit of JavaScript code that the JavaScript engine can evaluate, and return a value. Expressions can vary in complexity. We start from the very simple ones, called primary expressions: Arithmetic expressions are expressions that take a variable and an operator (more on operators soon), and result in a number: String expres...
Operators allow you to get two simple expressions and combine them to form a more complex expression. We can classify operators based on the operands they work with. Some operators work with 1 operand. Most work with 2 operands. Just one operator works with 3 operands. In this first introduction to operators, we'll introduce the operators you are m...
Jun 6, 2023 · Promises are a fundamental concept in JavaScript that allow us to handle asynchronous operations in a more elegant and structured way. They provide a powerful mechanism for managing the flow of asynchronous code, making it easier to write and reason about asynchronous tasks.
Jun 3, 2020 · Promises are used in JavaScript to handle async operations. They are special objects that link the actual output (in above example, it's required money) and the reason due to which we may not get the output (Account Frozen).
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May 25, 2022 · Get started. In JavaScript, a promise is a placeholder (proxy) for the value of an ongoing operation. You typically use a promise to manage situations where you must wait for the outcome of an operation. For example, uploading files to the server and awaiting the...
