More on JavaScript Operators

Read this article to learn more about using operators in JavaScript. We will not use all of them in this introductory course. However, this is a condensed reference that contains tables of all operator categories. JavaScript categorizes operators by the task (such as arithmetic, comparison, or assignment). Operators execute in a particular order. This is called operator precedence and tells JavaScript which part to evaluate first, second, third, and so on. This is an important concept.

For example, consider how a program calculates a price using arithmetic operators:

Multiplication first the result is: $18 = 4 + 2 * 7 ( 2 * 7 = 14 + 4)
Calculate left to right the result is: $42 = 4 + 2 * 7 (4+ 2 = 6 * 7)

String operators

In addition to the comparison operators, which can be used on string values, the concatenation operator (+) concatenates two string values together, returning another string that is the union of the two operand strings.

For example,

console.log('my ' + 'string'); // console logs the string "my string".

The shorthand assignment operator += can also be used to concatenate strings.

For example,

var mystring = 'alpha';
mystring += 'bet'; // evaluates to "alphabet" and assigns this value to mystring.