Best answer: What is Colon used for in JavaScript?

What is colon used for in TypeScript?

Back to colon vs equals

Type annotations means that TypeScript allows you to declare a variable’s type and then have it checked at compile time. Keeping this really simple, equals signs are used to assign the value to a variable. A colon is used to assign a type.

Should we use semicolon in JavaScript?

JavaScript semicolons are optional. … This is all possible because JavaScript does not strictly require semicolons. When there is a place where a semicolon was needed, it adds it behind the scenes. The process that does this is called Automatic Semicolon Insertion.

What is [] in TypeScript?

TypeScript, like JavaScript, allows you to work with arrays of values. Array types can be written in one of two ways. In the first, you use the type of the elements followed by [] to denote an array of that element type: let list : number[] = [1, 2, 3];

Is semicolon mandatory in TypeScript?

TypeScript follows the same ASI rules as JavaScript. Semicolons are technically not required in either language, save for a few rare, specific cases. It’s best to be educated on ASI regardless of your approach.

Do I need semicolons in react?

One camp writes code that includes semicolons. Their code looks a bit more like a language that actually requires semicolons, like C or PHP. The other camp leaves the semicolons off, relying on ASI to put them in automatically. … For example, React still includes semicolons in its docs, but Vue does not.

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Where do I need semicolons in JavaScript?

The rules of JavaScript Automatic Semicolon Insertion

when the end of the source code file is reached. when there is a return statement on its own line. when there is a break statement on its own line. when there is a throw statement on its own line.

What are 3 dots in JavaScript?

(three dots in JavaScript) is called the Spread Syntax or Spread Operator. This allows an iterable such as an array expression or string to be expanded or an object expression to be expanded wherever placed.

Should I learn JavaScript or TypeScript?

We frequently see the question “Should I learn JavaScript or TypeScript? “. The answer is that you can’t learn TypeScript without learning JavaScript! TypeScript shares syntax and runtime behavior with JavaScript, so anything you learn about JavaScript is helping you learn TypeScript at the same time.

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