JavaScript Tutorial >> Validations in JavaScript.

Now we will learn here in JavaScript Tutorial that using of client side JavaScript is an efficient way to validate the user input in web applications. When there are many fields in the form, the JavaScript validation becomes too complex.

A person might think it easy to find a complete radio & checkbox client-side validation JavaScript on the web. It would however be our opinion that such a person would be mistaken. We searched and searched for a JavaScript We could plug and play, so to speak. The reality was, it simply did not exist. Here we define some common live JavaScript validation or what some might call inline error messages to explain more.

These are reusable JavaScript functions for common validations, here you will learn the list of built-in JavaScript functions to make any kind of Validations in JavaScript.
It includes things like checking if a value is a number, integer, blank, and so on...
It also has generic routines for getting and setting the value of any type of input field, as well as checking if the value has changed.

Function for JavaScript Validation	Description of validating function.
isBlank	This JavaScript will return True if the value is whitespace, newlines, or tabs. Otherwise it will return False. Test Example of Is Blank in JavaScript.
isInteger	This JavaScript Function validated a number and returns True if the value is an integer, otherwise it will return False.
isNumeric	isNumeric validates the value of any variable and return True if the value is numerical value like (1.4, -4.56, etc), otherwise it will return False.
isDigit	idDigit Function validate a single character from 0-9 and return True if the value is a single character 0-9 else it returns False
setNullIfBlank	This setNullIfBlank JavaScript Function sets an input field's value to empty if it only contains whitespace, newlines, or tabs
setFieldsToUpperCase	setFieldsToUpperCase JavaScript Function sets values of input fields to their uppercase values.
disallowBlank	disallowBlank JavaScript function returns true if field is blank, alerts a message, and focuses cursor to field requiring an input. Otherwise returns false.
disallowModify	disallowModify JavaScript Function returns true if field has been modified, alerts a message to visitor, and focuses cursor to field that was changed. Otherwise disallowModify returns false.
getInputValue	getInputValue JavaScript Function returns the value of any input element, regardless of type. getInputValue returns a comma-separated list for multiple selects and multiple form fields with the same name.
setInputValue	setInputValue JavaScript Function sets the value of any input element, regardless of type.
getInputDefaultValue	getInputDefaultValue JavaScript Function returns the default value at page load time of any input element, regardless of type. getInputDefaultValue returns a comma-separated list for multiple selects and multiple form fields with the same name.
isChanged	isChanged JavaScript Function returns true if the current value of a form field does not equal the value when the page was loaded.

►Example of JavaScript IF Statement
►Example of JavaScript IF Else Statement
►Dynamic HTML Heading displaying with If Else Statement
►JavaScript Switch Statement
►Breaking JavaScript Switch Statement
►Example of conditional redirects with JavaScript.

►Enable or Disable Dropdown List Example.
►Getting Form ID of of The Dropdown List.
►Check how many number of items are in Dropdown List.
►Changing the Dropdown list size at run time.
►Enable multiple selection in dropdown at run time.
►Show the all items in Dropdown List.
►Check the index of selected Dropdown List item.
►Editing an item of Dropdown List.
►Delete an item from Dropdown List.

►Simple Calculator using Forms Example
►Light On/Off Example using Radio Buttons
►Radio Button Test Example
►Select your favorite browser Example
►Temperature Conversion Example
►Getting Form ID of of The Dropdown List.
►document.forms.length, Checking number of forms in document
►Double or Square using Radio Example
►document.getElementById in Document Object
►Check Box Selection Test
►Accessing an item of a form using Document Object
►document.getElementsByName in Document Object
►Checkbox Calculator Example
►Check/UnCheck All Checkboxes Example
►Manipulating the Value of a Text Field Example
►Detecting Text Field Events Example
►Change the background color with onFocus Example
►Swap the values of text boxes Example
►Less Clutter Example (Removing default text box value using onBlur and onFocus)
►Detecting Textarea Events Example
►Detecting Multiple Options Selected Example
►Jump to the next Text Box when the current box's maximum length has been reached.