Short Circuit Evaluation
Short Circuit Evaluation
Vanilla JS
In JavaScript, short-circuit evaluation is a technique that allows you to use logical operators (such as && and ||) to perform conditional evaluations in a concise way.
The && operator (logical AND) returns the first operand if it is falsy, or the second operand if the first operand is truthy.
For example:
const x = 0;
const y = 1;
console.log(x && y); // Output: 0 (the first operand is falsy, so it is returned)
console.log(y && x); // Output: 0 (the second operand is falsy, so it is returned)
The || operator (logical OR) returns the first operand if it is truthy, or the second operand if the first operand is falsy.
For example:
const x = 0;
const y = 1;
console.log(x || y); // Output: 1 (the first operand is falsy, so the second operand is returned)
console.log(y || x); // Output: 1 (the first operand is truthy, so it is returned)
Short-circuit evaluation can be useful in cases where you want to perform a certain action only if a certain condition is met, or you want to return a default value if a certain condition is not met.
For example:
function displayName(name) {
return name || 'Anonymous';
}
console.log(displayName('Pizza')); // Output: "Pizza"
console.log(displayName()); // Output: "Anonymous"
In this example, the displayName() function returns the name property of the user object if it exists, or “Anonymous” if the name property is not present. This is done using the || operator and short-circuit evaluation.