JavaScript: Variables

When you start writing advanced JavaScript code that contains a lot of complex information, you need a way to simplify and manipulate the information. JavaScript uses variables to simplify the statements and work with information. The variables act as containers to hold values.

You list the variables before the statements, like this:

var area = 4000;
var size = 200;

In this case, area is a variable, and its value is assigned to be 4000. size is also a variable, with a value of 200.

You can also list multiple variables by separating the variables with commas on the same line, like this:

var area = 4000, size = 200, distance = 100;

Variables must be one word and can contain both letters and numbers (but can't start with numbers).

If the variable stores text (such as a phrase), the text is called a string. Strings are enclosed in quotes.

var welcome = "Welcome to the application.";

Single quotes are also acceptable instead of double quotes, but you must be consistent. You can't start with a double quote and end with a single quote.

About Tom Johnson

I'm an API technical writer based in the Seattle area. On this blog, I write about topics related to technical writing and communication — such as software documentation, API documentation, AI, information architecture, content strategy, writing processes, plain language, tech comm careers, and more. Check out my API documentation course if you're looking for more info about documenting APIs. Or see my posts on AI and AI course section for more on the latest in AI and tech comm.

If you're a technical writer and want to keep on top of the latest trends in the tech comm, be sure to subscribe to email updates below. You can also learn more about me or contact me. Finally, note that the opinions I express on my blog are my own points of view, not that of my employer.