JavaScript and JQuery: Interactive Front-End Web Development

4

DECISIONS & LOOPS

Looking at a flowchart (for all but the most basic scripts), the code can take more than one path, which means the browser runs different code in different situations. In this chapter, you will learn how to create and control the flow of data in your scripts to handle different situations.

Scripts often need to behave differently depending upon how the user interacts with the web page and/or the browser window itself. To determine which path to take, programmers often rely upon the following three concepts:

EVALUATIONS

You can analyze values in your scripts to determine whether or note they match expected results.

DECISIONS

Using the results of evaluations, you can decide which path your script should go down.

LOOPS

There are also many occasions where you will want to perform the same set of steps repeatedly.

DECISION MAKING

There are often several places in a script where decisions are made that determine which lines of code should be run next. Flowcharts can help you plan for these occasions.

In a flowchart, the diamond shape represents a point where a decision must be made and the code can take one of two different paths. Each path is made up of a different set of tasks, which means you have to write different code for each situation.

In order to determine which path to take, you set a condition. For example, you can check that one value is equal to another, ...