The difference between the two is perhaps a bit more clear through code: let a Ĭonsole.log(a) // undefined let b = null Ī is undefined - it's not assigned to anything, and there's no clear definition as to what it really is. null is a variable that is defined but is missing a value.undefined is a variable that refers to something that doesn't exist, and the variable isn't defined to be anything.Though, there is a difference between them: ![]() ![]() Undefined and null variables often go hand-in-hand, and some use the terms interchangeably. In this short guide, we'll take a look at how to check if a variable is undefined or null in JavaScript. Whether we lose a reference through side-effects, forget to assign a reference variable to an object in memory, or we get an empty response from another resource, database or API - we have to deal with undefined and null values all the time. Typically, this means we need to use an ifâ¦else statement to determine if the item exists using the returned index.Undefined and null values sneak their way into code flow all the time. ![]() In JavaScript, 0 is a falsy value, while numbers less than or greater than 0 are considered truthy. This method returns the index position of the item if it exists in the array and returns -1 if it does not. We can look up the existence of an item in an array using the Array.indexOf method. If (str != null & str != undefined & str != '') `)Īrray.indexOf shorthand using the bitwise operator The following example demonstrates how to use short-circuit evaluation: // Longhand This shorthand uses the logical OR operator || to assign a default value to a variable when the intended value is falsy. Short-circuit evaluationĪnother way to replace an ifâ¦else statement is with short-circuit evaluation. Once there are more than two outcomes to your condition, using if/else blocks are much easier to read. The ternary operator is great when you have single-line operations like assigning a value to a variable or returning a value based on two possible conditions. The following example demonstrates a traditional ifâ¦else statement and its shorthand equivalent using the ternary operator: // Longhand It replaces the traditional ifâ¦else statement. The ternary operator is one of the most popular shorthands in JavaScript and TypeScript. The only slight differences are in specifying the type in TypeScript, and the TypeScript constructor shorthand is exclusive to TypeScript. Keep this in mind when using the following shorthands for expressions and operators in JavaScript and TypeScript.Īll shorthands available in JavaScript are available in the same syntax in TypeScript. Our decision to use shorthands must not be detrimental to other desirable code characteristics. So, it is important that your code is legible and conveys meaning and context to other developers. Concise code can sometimes be more confusing to read and update. Using shorthand code is not always the right decision when writing clean and scalable code. But there is more to it than meets the eye. The operator is used in conditional statements, and when paired with a :, can function as a compact alternative to if.else statements. Implicit return using arrow function expressions The conditional or question mark operator, represented by a, is one of the most powerful features in JavaScript.Array.indexOf shorthand using the bitwise operator.Read through these useful JavaScript and TypeScript shorthands or navigate to the one youâre looking for in the list below. ![]() We will also explore examples of how to use these shorthands. In this article, we will review 18 common JavaScript and TypeScript and shorthands. easy way to execute conditional html / javascript / css / other language code with php if else: html code to run if condition is.Shorthand code alternatives can help reduce lines of code, which is something we typically strive for. JavaScript and TypeScript share a number of useful shorthand alternatives for common code concepts. 18 JavaScript and TypeScript shorthands to knowÄ®ditorâs note: This guide to the most useful JavaScript and TypeScript shorthands was last updated on 3 January 2023 to address errors in the code and include information about the satisfies operator introduced in TypeScript v4.9. When she's not writing code, she likes to read, listen to music, and put cute outfits together. Ibiyemi Adewakun Follow Ibiyemi is a full-stack developer from Lagos.
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