Operators
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:
Math.abscalculates the absolute value of a numberMath.expcalculates e to the power of a numberMath.pow(x,y)calculates the result of x to the power of yMath.floorremoves the fraction part from a numberMath.random()will give a random numberxwhere 0<=x<1
Exercise:
In this exercise, you do the following:
- Connect the
firstNameandlastNameto construct the variablefullName, but with a space (" ") in between the first and last name. - Multiply the variable
myNumberby 2 and put the result inmeaningOfLife.
