Tham khảo sách 'javascript bible_ chapter 53', công nghệ thông tin, kỹ thuật lập trình phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Application Decision Helper The list of key concepts for this chapter s application looks like the grand finale to a fireworks show. As JavaScript implementations go the application is in some respects over the top yet not out of the question for presenting a practical interactive application on a Web site lacking control over the server. The Application I wanted to implement a classic application often called a decision support system. My experience with the math involved here goes back to the first days of Microsoft Excel. More recently I put the concepts to work for the former MacUser magazine in an application that assisted Macintosh shoppers in selecting the right model for their needs. Rather than design a program that had limited appeal covering only one possible decision tree I set out to make a completely user-customizable decision helper. All the user has to do is enter values into fields on a number of screens the program performs the calculations to let the user know how the various choices rank. Although I won t be delving too deeply into the math inside this application it s helpful to understand how a user approaches this program and what the results look like. The basic scenario is a user who is trying to evaluate how well a selection of choices measure up to his or her expectations of performance. User input includes the following 4- The name of the decision 4 The names of up to five alternatives people products ideas and so on 4 The factors or features of concern to the user 4 The importance of each of the factors to the user 4 A user ranking of the performance of every alternative in each factor 4- 4 4 In This Chapter Multiple frames Multiple-document applications Multiple windows Persistent storage cookies Scripted image maps Scripted charts 4- 4- 4- 74 JavaScript Applications What makes this kind of application useful is that it forces the user to rate and weigh a number of often-conflicting factors. By assigning hard numbers to these elements
