CODEWITHSUNDEEP
javascriptreactjsarrow-functions
Atul
Atul

Reputation: 21

Role of () bracket after arrow?

This line works as the content after arrow in wrapped in ()

this.setState((prevState) => ({toggle:prevState.toggle + 1}))

The content after arrow is not wrapped in () so it is not working

this.setState((prevState) => {toggle:prevState.toggle + 1})

Upvotes: 1

Views: 94

Answers (2)

Jagrati
Jagrati

Reputation: 12222

Arrow functions may implicitly return values by simply omitting the curly braces that traditionally wrap a function's body if their body only contains a single expression.

const foo = x => x + 1;
foo(1); // -> 2

When using implicit returns, object literals must be wrapped in parenthesis so that the curly braces are not mistaken for the opening of the function's body.

const foo = () => { bar: 1 } // foo() returns undefined
const foo = () => ({ bar: 1 }) // foo() returns {bar: 1}

Upvotes: 4

gautamits
gautamits

Reputation: 1292

When you want to implicitly return an object, curly braces do not work because they denote start and end of block. In order to distinguish between block and JS object, you wrap the object in ().

Upvotes: 1

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