// Statements
let x = 0;
function add(a, b) { return a + b; }
if (true) { console.log('Hi'); }
// Expressions
x; // Resolves to 0
3 + x; // Resolves to 3
add(1, 2); // Resolves to 3
//statement
A statement is an instruction to perform a specific action. Such actions include creating a variable or a function, looping through an array of elements, evaluating code based on a specific condition etc. JavaScript programs are actually a sequence of statements.
//expression
Any unit of code that can be evaluated to a value is an expression. Since expressions produce values, they can appear anywhere in a program where JavaScript expects a value such as the arguments of a function invocation.