JavaScript, often abbreviated as JS, is a programming language that conforms to the ECMAScript specification. JavaScript is high-level, often just-in-time compiled, and multi-paradigm. It has curly-bracket syntax, dynamic typing, prototype-based object-orientation, and first-class functions.
Expressions rely on things called operators; they allow programmers to create a single value from one or more values. Several arithmetic operations can be performed in one expression, but it is importantto understand how the result will be calculated. Multiplication and division are performed before addition or subtraction. This can affect the number that you expect to see. To illustrate this effect, look at the following examples.
There is just one string operator: the+ symbol. It is used to join the strings on either side of it.
Browsers require very detailed instructions about what we want them to do. Therefore, complex scripts can run to hundreds (even thousands) of lines. Programmers use functions, methods, and objects to organize their code.
Functions let you group a series of statements together to perform a specific task. If different parts of a script repeat the same task, you can reuse the function (rather than repeating the same set of st atements).