Difference between expressions and statements?

1. 表达式返回的是值，可以直接打印出来；

5 + 5 // => 10

lastCharacter("input") // => "t"

true === true // => true

2. 语句是执行的某种操作

let x = 0

function declaration() {}

if (true) {
}

3. Expression statement: produces a value and performs an action

// Assign `x` as the absolute value of `y`.
var x = y >= 0 ? y : -y