JavaScript For Loop and Nested Loops with Arrays and Error Handling, Study notes of Computer Science

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Announcements

 Check class announcements daily

 You must implement programming projects by yourself

For Loop

 Iteration statement  General form for (initialize; test; expression) statement basically equivalent to Initialize while (test) { statement expression }  If more than one statement use { }  Semicolons are required  Beware of infinite loop if semicolon after )  Example: ForLoop.html  Example: ForLoopVariations.html

One-Dimensional Arrays

 Problem  You need to keep track of the scores of students in a class  Declaring and handling 50 variables is not an easy task  Arrays come to the rescue  Array  Collection of values that can be treated as a unit or individually var a = new Array(4)  You can visualize an array as a set of variables one after another  Indexing We access an element using [ ]  First element associated with index 0 (e.g., a[0])  An element of an array can be of any type and an array can hold different types of elements  The length property represents the length of the array (e.g., a.length)  We can print the contents of an array by using alert  Example: ArrayEx.html

Definition of One-Dimensional Arrays  Via array literal  comma separated list of elements within square brackets var a = [2, 3, 5]; var b = []; // empty array  Specified in the Array constructor var c = new Array(); var e = new Array(4); // defines array of size 4

 What is Top-Down Design?

 Let’s go over an example

Video Store Software

 Bottom-Up Design

Top-Down Design