Concise Body Arrow Functions

JavaScript also provides several ways to refactor arrow function syntax. The most condensed form of the function is known as concise body. We’ll explore a few of these techniques below:

  1. Functions that take only a single parameter do not need that parameter to be enclosed in parentheses. However, if a function takes zero or multiple parameters, parentheses are required.

    showcasing how arrow functions parameters differ for different amounts of parameters
  2. A function body composed of a single-line block does not need curly braces. Without the curly braces, whatever that line evaluates will be automatically returned. The contents of the block should immediately follow the arrow => and the return keyword can be removed. This is referred to as implicit return.

comparing single line and multiline arrow functions

So if we have a function:

const squareNum = (num) => { return num * num; };

We can refactor the function to:

const squareNum = num => num * num;

Notice the following changes:

  • The parentheses around num have been removed, since it has a single parameter.
  • The curly braces { } have been removed since the function consists of a single-line block.
  • The return keyword has been removed since the function consists of a single-line block.



Let’s refactor plantNeedsWater() to be a concise body. Notice that we’ve already converted the if/else statement to a ternary operator to make the code fit on one line.

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