JavaScript: Operators

In mathematics and programming, we often use operation signs such as +, -, *, and others. In programming, such signs are called operators.

• An operator is a symbol or word that denotes an action.
• Operands are the values to which the operator is applied.

Example:

console.log(8 + 2);

Here:

• + is an operator
• 8 and 2 are operands
• the result will be 10

operand   operator   operand       result
    8         +          2       →      10
    5         -          3       →      2
    4         *          3       →      12

Unary operators

There are also unary operations that work with a single operand. Example:

console.log(-3); // => -3

In this case, - is a unary operator, and 3 is the operand. The interpreter receives the command: "take the number 3 and change its sign".

The - operator can be used in different ways. When it stands between two numbers, it is a subtraction operation:

console.log(5 - 2);   // => 3
console.log(10 - 7);  // => 3

This difference is especially noticeable when working with negative numbers:

// minus times minus gives plus
console.log(5 - -2); // => 7

First we see the subtraction operation: 5 - (...). But on the right there is a unary minus -2, which turns 2 into a negative number. As a result, we get: 5 - (-2) = 7.

Thus, the meaning of - depends on the context: if there is another number next to it, it is subtraction; otherwise, it is a change of the number's sign.

Errors in calculations

If you treat -3 as a single number, you might not notice that - is a separate operator with its own priority. For example:

console.log(-3 ** 2); // => -9, not 9!

At first glance, it might seem that -3 is being squared, and the result should be 9. But the result will be -9.

The reason lies in the order of calculations: first the exponentiation (**) is performed, and only then the unary minus is applied. That is: -(3 ** 2) = -9. We will talk about operator priority in more detail in the following lessons.

A submarine is at a depth of -81 m. The deck of the rescue ship is located at a height of +6 m above the water level.

Calculate and print to the screen:

1. The total ascent distance in meters.
2. The ascent time in minutes — the submarine rises at a speed of 3 m/min.