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Tutorial 10 – Session 2

Tutorial 10 – Session 2. Programming with JavaScript. Objectives. Learn about JavaScript data types Declare and work with variables Create and call a JavaScript function. Working with Variables. A variable is a named item in a program that stores information

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Tutorial 10 – Session 2

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  1. Tutorial 10 – Session 2 Programming with JavaScript

  2. Objectives Learn about JavaScript data types Declare and work with variables Create and call a JavaScript function New Perspectives on HTML and XHTML, Comprehensive

  3. Working with Variables A variable is a named item in a program that stores information Most JavaScript programs use variables to represent values and text strings New Perspectives on HTML and XHTML, Comprehensive

  4. Declaring a JavaScript Variable You can declare variables with any of the following JavaScript commands: var variable; var variable = value; variable = value; where variable is the name of the variable and value is the initial value of the variable. The first command creates the variable without assigning it a value; the second and third commands both create the variable and assign it a value New Perspectives on HTML and XHTML, Comprehensive

  5. Working with Variables and Data JavaScript variable types: Numeric variables String variables Boolean variables Null variables You must declare a variable before using it New Perspectives on HTML and XHTML, Comprehensive

  6. Working with Variables and Data Numeric variable- any number, such as 13, 22.5, etc. Can also be expressed in scientific notation String variable- any group of text characters, such as “Hello” or “Happy Holidays!” Must be enclosed within either double or single quotations (but not both) Boolean variable- accepts only true and false values Null variable- has no value at all New Perspectives on HTML and XHTML, Comprehensive

  7. Working with Variables and Data JavaScript is a weakly typed language The + symbol can be used with either numeric values or text strings var total = 5 + 4; var emLink = "cadler" + "@" + "mpl.gov"; New Perspectives on HTML and XHTML, Comprehensive

  8. Creating a JavaScript Function A function is a collection of commands that performs an action or returns a value A function name identifies a function Parameters are values used by the function The function is executed only when called by another JavaScript command function_name(parameter values) New Perspectives on HTML and XHTML, Comprehensive

  9. Creating a JavaScript Function New Perspectives on HTML and XHTML, Comprehensive

  10. Creating a Function to Return a Value For a function to return a value, it must include a return statement function function_name(parameters){ JavaScript commands return value; } New Perspectives on HTML and XHTML, Comprehensive

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