7 Essential JavaScript Functions

JavaScript, along with HTML5 and CSS3, is nowadays used widely by developers for developing responsive web applications that look good on both desktop computers and mobile devices. Despite being a client-side scripting language, JavaScript provides a number of features that help users to build robust websites without writing longer lines of code. Also, JavaScript enables programmers to reducing coding time by using a variety of pre-built functions. As a group of reusable code, functions allow programmers to make the codebase modular, and avoid writing the same piece of code repeatedly. The programmers also have option to take advantage of several pre-built functions in JavaScript.

Overview of 7 Commonly Used JavaScript Functions

1) prompt()

While designing a web page, developers often require users to input a specific value before accessing the web page. This pre-built function helps programmers to prompt users to ask an input value through a prompt box. After entering the value, the user has to click either on the OK or Cancel button to access the page. But no user can access the web page without closing the prompt dialog box. Also, the developers can capture the input value received through prompt() to display more personalized content to each user.

2) alert()

Despite being a simple JavaScript function, alert() is used commonly by both beginners and experienced programmers. The function helps programmers to convey a specific message to users through a dialog box. The dialog box will shift the cursor from the web page, and compel the user to read the message. The users can close the dialog box by simply clicking on the OK button. Often programmers use alert() to make users submit the most appropriate input values through forms.

3) decodeURI()

Often the whitespaces, spaces and similar characters in a URI cause parsing problems. So developers have to replace such characters with the relevant Unicode characters. The built-in JavaScript function helps programmers to eliminate chances of parsing errors by replacing such characters with their Unicode equivalents. They can also use decodeURIComponent() additionally to identify and decode the standard components of the URI.

4) validate()

While designing a web page, programmers often use forms as a tool to receive user inputs. However, they still need to validate the accuracy of the information submitted by a user. The simple functions helps programmers to validate data when the user clicks on the submit button. Hence, validate() is called each time the onsubmit event occurs. The developers also have option to make users submit the right input values by displaying custom error messages through alert(). But they often use validate() to validate user data without writing additional and complex code.

5) setTimeout() and setInterval()

Often JavaScript developers use these two functions together to create simple animations. The setTimeout() function accepts two parameters, i.e., a function and the duration. Each time setTimeout() is invoked, the specific function is executed at the duration mentioned in milliseconds. At the same time, the setInterval() function also accepts the same parameters. It calls the function at the predefined intervals in milliseconds. The programmers use these functions to rotate images and other HTML elements periodically, and add animations to the web page without using additional tools.

6) onload()

Each time a web page is loaded, the browser processes the code from top to bottom order. HTML, CSS, JavaScript or PHP code is processed in the same order. But the developers have option to change the order of code execution by using the onload function. They can use the functions to make the browser understand the sequence of code execution. Each time the web page is loaded, the specific function will be executed. Hence, the user can access the page or see web page content based on the code included in the onload function.

7) toString()

Often developers have to validate a value by asking users to confirm the input submitted by you. Hence, they have to display the values as string regardless of their data types. The developers can use toString() with a variety of objects to display their value as character. However, they cannot manipulate the value converted into string or make any changes to the original value or data type o the variable.

Recently i have written an article about Needs of JavaScript for developers. It is always important for the developers to pick the right JavaScript functions based on their requirements. In addition to using these pre-built functions, they also have option to write custom functions to accomplish specific tasks. However, they can call both pre-built and custom functions from anywhere in the program. JavaScript even allows developers to divide the large programs into a number of small and manageable functions.