You can access history via window.history that contains the browserвЂ™s history.

Converts to NaN with primitive operations.ДЈ7.

Represents the absence of the variable.

Is a value that represents a variable that has been declared but doesnвЂ™t have a value.

Converts to 0 with primitive operations.

Represents the absence of a value of a variable.

Represents null, empty, or non-existent reference.

Is a value that indicates the variable points to no object.

The type of null is an object: var name = null console.log(typeof(name)) 36. E.g id retrieved from ManufacturerType will be Manufacturer. It highlights that a variable points to no object. Hooks action Customer FormBuilderModifier, actionAfterCreate Customer FormHandler and actionAfterUpdate Customer FormHandler are built using unique identifier which in this case is Customer is retrieved from its form type CustomerType. typeof 'John Abraham' // Returns 'string' typeof 100 // Returns 'number' 35.

How can you check the type of a variable in JavaScript? LetвЂ™s see an example use of each: AlertДЇor example: window.alert('Hello, world!') ConfirmДЇor example: if (nfirm('Are you sure you want to go?')) 34. The three types of popups are alert, confirm, and prompt. What types of popup boxes are there in JavaScript? If the program tries to read an undefined variable, an undefined value is returned and the app does not crash.ДЄn example of an undefined variable is: let car console.log(car) Undefined variables are declared in the program but donвЂ™t have a value.Output: error: Uncaught ReferenceError: dog is not defined If your program tries to read an undeclared variable, a runtime error is thrown.ДЄn example of calling an undeclared variable obviously results in an error: console.log(dog) Undeclared variables do not exist in a program at all.What is an undeclared variable? How about an undefined variable? You get a negative infinity if you divide a negative number with zero in JavaScript. You can write various small functions, called event handlers using any of the scripting. This script could be written using JavaScript or VBScript. For example, a script could generate a pop-up alert box message, or provide a dropdown menu. Output: Not a Number! Cannot be a weight. A script is a small piece of program that can add interactivity to your website.

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