Tutorial
Every variable in JavaScript is casted automatically so any operator between two variables will always give some kind of result.
The addition operator
The +
(addition) operator is used for both addition and concatenation of strings.
For example, adding two variables is easy:
var a = 1;
var b = 2;
var c = a + b; // c is now equal to 3
The addition operator is used for concatenating strings to strings, strings to numbers, and numbers to strings:
var name = "John";
console.log("Hello " + name + "!");
console.log("The meaning of life is " + 42);
console.log(42 + " is the meaning of life");
JavaScript behaves differently when you are trying to combine two operands of different types. The default primitive value is a string, so when you try to add a number to a string, JavaScript will transform the number to a string before the concatenation.
console.log(1 + "1"); // outputs "11"
Mathematical operators
To subtract, multiply and divide two numbers, use the minus (-
), asterisk (*
) and slash (/
) signs.
console.log(3 - 5); // outputs -2
console.log(3 * 5); // outputs 15
console.log(3 / 5); // outputs 0.6
Advanced mathematical operators
JavaScript supports the modulus operator (%
) which calculates the remainder of a division operation.
console.log(5 % 3); // outputs 2
JavaScript also supports combined assignment and operation operators. So, instead of typing myNumber = myNumber / 2
, you can type myNumber /= 2
. Here is a list of all these operators:
/=
*=
-=
+=
%=
JavaScript also has a Math
module which contains more advanced functions:
Math.abs
calculates the absolute value of a numberMath.exp
calculates e to the power of a numberMath.pow(x,y)
calculates the result of x to the power of yMath.floor
removes the fraction part from a numberMath.random()
will give a random numberx
where 0<=x<1
And many more mathematical functions.
Exercise
In this exercise, you do the following:
- Connect the
firstName
andlastName
to construct the variablefullName
, but with a space (" "
) in between the first and last name. - Multiply the variable
myNumber
by 2 and put the result inmeaningOfLife
.
Tutorial Code
var firstName = "John";
var lastName = "Smith";
var myNumber = 21;
// TODO: change the following code
var fullName = null;
var meaningOfLife = null;
console.log("The name is " + fullName);
console.log("The meaning of life is " + meaningOfLife);
Expected Output
The name is John Smith
The meaning of life is 42