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Logical Operators

Easy

In plain terms

&& (AND) returns the first falsy or last value. || (OR) returns the first truthy or last value. ! (NOT) inverts to boolean. Use for conditionals and short-circuit evaluation.

What you need to know

  • •&& AND, || OR, ! NOT
  • •Short-circuit evaluation
  • •Return original values, not just boolean

Try it yourself

Copy the code below and run it in your browser console or a code editor:

true && true;   // true
true && false;  // false

null || 'default';  // "default" (first truthy)
'' || 'fallback';   // "fallback"

!true;   // false
!!'hi';  // true (double NOT for boolean)

// Short-circuit
const user = null;
const name = user && user.name;  // null (no error)

Learn more

Dive deeper with these trusted resources:

MDNjavascript.infoTutorialsPointW3Schools