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Lecture Introduction to web engineering - Lec 23: History, navigator, screen and form objects

Lecture Introduction to web engineering - Lec 23: History, navigator, screen and form objects. After studying this chapter you will be able to understand: History object, navigator object, screen object, form object, accessing form elements, setting form elements, validating form data. | Basharat Mahmood, Department of Computer Science, CIIT, Islamabad, Pakistan 1 Controlling the background dynamically Bgcolor Text background Working with images Image rollover Image preview Image slide show Date object Digital clock Basharat Mahmood, Department of Computer Science, CIIT, Islamabad, Pakistan 2 History object Navigator object Screen object Form object Basharat Mahmood, Department of Computer Science, CIIT, Islamabad, Pakistan 3 Basharat Mahmood, Department of Computer Science, CIIT, Islamabad, Pakistan 4 The history object contains the URLs visited by the user (within a browser window) The history object is part of the window object and is accessed through the window.history property Used to move forward and backward through the visitor’s browsing history Basharat Mahmood, Department of Computer Science, CIIT, Islamabad, Pakistan 5 History object properties: Length: Returns the number of URLs in the history list History object methods: back(): Loads the previous URL in | Basharat Mahmood, Department of Computer Science, CIIT, Islamabad, Pakistan 1 Controlling the background dynamically Bgcolor Text background Working with images Image rollover Image preview Image slide show Date object Digital clock Basharat Mahmood, Department of Computer Science, CIIT, Islamabad, Pakistan 2 History object Navigator object Screen object Form object Basharat Mahmood, Department of Computer Science, CIIT, Islamabad, Pakistan 3 Basharat Mahmood, Department of Computer Science, CIIT, Islamabad, Pakistan 4 The history object contains the URLs visited by the user (within a browser window) The history object is part of the window object and is accessed through the window.history property Used to move forward and backward through the visitor’s browsing history Basharat Mahmood, Department of Computer Science, CIIT, Islamabad, Pakistan 5 History object properties: Length: Returns the number of URLs in the history list History object methods: back(): Loads the previous URL in the history list forward(): Loads the next URL in the history list go(): Loads a specific URL from the history list Basharat Mahmood, Department of Computer Science, CIIT, Islamabad, Pakistan 6 Writes history length on webpage Go back function Go forward functions Basharat Mahmood, Department of Computer Science, CIIT, Islamabad, Pakistan 7 Body contents Call to go back Call to goforward The navigator object contains information about the browser provides several properties that assist in the detection of various elements of the visitor’s browser and environment Basharat Mahmood, Department of Computer Science, CIIT, Islamabad, Pakistan 8 Navigator object properties: appCodeName: Returns the code name of the browser appName: Returns the name of the browser appVersion: Returns the version information of the browser Navigator object methods: javaEnabled(): Specifies whether or not the browser has Java enabled Basharat Mahmood, Department of Computer Science, CIIT, Islamabad, Pakistan 9 .