Implicit vs. Explicit Return in ES6 Arrow Functions: When Should I Use Which?

Implici Return or Explicit Return in ES6 Arrow Functions: When to Use

ES6 introduced arrow functions, offering a concise and implicit way of writing functions. By default, the return value is implicit under certain circumstances. However, there are instances when an explicit return statement is necessary.

Implicit Return:

If an arrow function consists of a single expression enclosed in parentheses without a block, the expression is implicitly returned as the value of the function.

Example:

const greet = (name) => 'Hello, ' + name;
console.log(greet('John')); // Output: Hello, John

Explicit Return:

1. Blocks: Arrow functions with a block delimitation using curly brackets require an explicit return statement to define the return value.
2. Multiple Lines: If an arrow function expression expands to multiple lines without a block, an explicit return is needed. Otherwise, it will result in a SyntaxError.
3. Syntactic Ambiguity: Arrow functions with braces that resemble block statements but are actually labels may result in undefined return values. To avoid this, use an explicit return.

Examples:

// No block, implicit return
const implicit = (name) => {id: name};
console.log(implicit('Jane')); // Output: {id: 'Jane'}

// Block without explicit return
const blockWithoutReturn = (name) => {...};
console.log(blockWithoutReturn('Joe')); // Output: undefined

// Block with explicit return
const blockWithReturn = (name) => {return {id: name}};
console.log(blockWithReturn('Jill')); // Output: {id: 'Jill'}

In summary, while implicit return is convenient for concise arrow functions with a single expression, explicit returns are necessary for blocks, multiline expressions, and potential syntactic ambiguity.

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