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The JetBrains applications run on Windows. J Internet Explorer. When it comes to the browser as debugging and development software. If everyone accessing a Web site was only using the same version of the same browser with the same screen resolution and roughly the same connection speed. As you know. For each. Your enemy To use the Web.
I normally surf using Safari. I find this arrangement works well for me because Safari does not have all the development tools I want. To develop Web sites.. It has become a challenge to test a site on even a small subset of the potential clients. In this section. As a point of reference.
MiCrosoFt internet exPlorer And then.
In part. On the other hand. Because lots of regular people are using IE. The fact is that. What can I say about IE? The best advice I can give you regarding browsers is this: Get your site working perfectly using another browser. But still… With that diatribe out of the way. Opera has often been at the forefront of supporting emerging technologies. More current versions of Safari include a collection of a developer tools.
But Safari has become an extremely important browser over the past couple of years. Safari www. By being the default browser on the iPhone. Although Safari is available on Windows.
If you have one computer. These services provide snapshots of how your page rendered in a long list of browsers. This is a challenge. This is great. Spoon is free. One option is to purchase multiple computers. There are other options that require no installation on your computer and no maintenance of multiple operating systems.
In order to be able to perform live testing of your site in multiple browsers. A second option is to use virtualization software on your computer. This is not an unreasonable solution. Manufacturers of most devices or device operating systems also provide emulators for you to use to test your software or Web site.
A couple of these services also offer up mobile virtualization.
Without creating an HTML page. Manipulate the HTML. Use the View check boxes to dictate which panes you want visible. Use the vertical dividers to resize the panes as needed. Load www. JS Bin provides up to three panes: You ought to look at the help and tutorials pages.
An alternative to JS Bin is jsFiddle www. Press Escape to close the keyboard shortcuts window. The intent is the same.
What You Will Learn
You cannot use one of those reserved words as the name of your variable or function. J An imbalance of quotation marks.
Using a single equals sign when you should use two leads to logical errors. Using Control Structures. This topic was also discussed earlier in the chapter: One such site is JSLint www.
Just as there are HTML validation services. JSHint serves the same purpose. For better or for worse. J Get a good text editor or IDE.
But this is highly effective. J Take a break! Eat an apple. When all else fails. Isolating the specific browsers that are experiencing the problem can help you more quickly determine the underlying cause.
Note that Firebug was originally developed for the Firefox Web browser. I want to provide a brief introduction to using Firebug here. Although the Web developer tools now shipping with Safari i. Opera Dragonfly. And you can enter clear. Within a blank Web page. If there are any errors in the page. Clicking the first an inverted chevron minimizes Firebug but keeps it active.
At the top of the Script panel. This is useful. This is a huge debugging asset. To set a breakpoint in Firebug. Note that the breakpoint takes effect before that line is executed. My recommendation is to get in the habit of using it. Step Over. This establishes a breakpoint when the window.
Step Into. In the resulting pop-up. There are oodles of tutorials and screencasts online for how to use it. The meanings of these can be a bit confusing for those new to Firebug. When you feel ready to learn more. Watch expressions are most commonly used to set breakpoints based upon the value of a variable.
These will be discussed in Chapter Beyond those sites. J Brendon Eich http: Ruby www. You can find the pages associated with this book at my Web site. And in the previous chapter.
If you have any questions or problems. The most important debugging step. Maybe you should take a quick break now. All programming comes down to taking some action with some data.
That line would most likely cause a logical or run-time error. As discussed in Chapter 1. If fullName stores a quoted sequence of zero or more characters. The semicolon is used to terminate a statement. Note that each variable is only declared once. Other languages. This can happen if your code has a variable with the same name as a poorly designed library you might also be including in the same page. If a variable does not absolutely need to be global. There are a few reasons to avoid using global variables.
Variables declared outside of any function. They only exist within that function. By comparison.. Variables declared outside of any functions should be declared at the top of the code. As a final note on the var keyword.
In Chapter 5. That syntax. Some of the operators in Table 4. The increment operator adds one to the value of the variable. A difference between the postfix and prefix versions is a matter of operator precedence.
Each input is given a default value. The final text element will be updated with the results of the calculation. The most relevant HTML is: Creating CalCulators At this point in time. The other types are simply text. J Mortgage and similar loan calculators J Temperature and other unit conversions J Interest or investment calculators For this particular example. Remember that as Chapter 2. Note that in the Chapter 2 example. As mentioned previously. At this point in time. In these four lines of code.
But as Chapter 5 more formally covers the knowledge needed to perform validation. Begin defining the calculate function: It does the actual work. This function will be called when the user clicks the submit button. Get references to the form values: Declare a variable for storing the order total: To create a calculator: Calculate the initial total: There are a couple of ways one can calculate and add in the tax. Factor in the discount: The discount is just being subtracted from the total.
An alternative way to calculate the tax would be to convert it to decimal. The total variable is first assigned the value of the quantity times the price.
You could also make use of precedence and parentheses to perform all these calculations in one line. Display the total in the form: Factor in the tax rate: This code could also be written more formally: The first.
Define the init function: Return false to prevent submission of the form: The value attribute can also be used to assign a value to a text form input. In later chapters. Using this approach. The init function will be called when the window triggers a load event see Step Complete the function: It says that when the window has loaded.
This code was also explained in Chapter 2. To improve the professionalism of the calculator. Play with the numbers. Another problem. That knowledge will be taught in the next chapter. ForMatting nuMBers Although the previous example is perfectly useful. That function references calculate. Save the file as shopping. As an object. To format a number: It takes an argument dictating the total number of significant digits. This method returns a number with a set number of digits to the right of a decimal point: Similar to toFixed is toPrecision.
This one line will take care of formatting the decimal places. After factoring in the discount. Open shopping. Remember that the returned result must be assigned back to the variable in order for it to be represented upon later uses.
Secondarily, compiled applications make seeing the underlying code anywhere from hard to impossible.
As of August 1, , Google decided to start supporting a more modest list of modern browsers supporting for Web applications; the Google search engine is usable in any browser, of course. Googles criteria is simply the most current release of Chrome, Firefox, IE, and Safari, plus the preceding release of each.
Top Reviews Most recent Top Reviews. There was a problem filtering reviews right now. Please try again later. Kindle Edition Verified Purchase.
I'm very pleased with the progression of concepts and the exercise samples used to demonstrate these concepts. We start simple with variable assignment and simple calculations.
I also have to make my own personal changes to things like variable and file names. So, while I downloaded and reviewed the sample code for reference - I purposely avoid using any of that code I'm not trying to learn how to download and get someone else's code to work: I also need my development toolbox - which includes the following YMMV - you'll probably need some working knowledge of similar tools: Firebug and Firebug lite - console commands, break points and watch vars 3.
Netbeans - IDE for PHP breakpoints If exercises and a workbook approach is your idea of fun like it is for me you will enjoy this book.
Excellent resource. Paperback Verified Purchase. Not only is the book well organized, but the writing style is very conversational and easy to understand. Exercises are appropriate and interesting, modeled to test what you learned in each section. Ullman does an excellent job of presenting techniques along with good coding practices. The simply designed cover belies the visually rich treasure trove within. Reviewing texts for potential classroom use can be tedious. I often do it at night right before bed.
I couldn't do that with this book. There were so many new things to try, I kept firing up my laptop to test them out. I can't get enough of it. It's too late in the school year to use for my upcoming class; I wish I had found it earlier.
It's definitely on the list for the future though! I don't know if this book was written before the author came out with his PHP and MySQL for dynamic web sites, but it isn't even close to being as good of a book.
It is very confusing. I found myself reading chapters over and over and still not understanding. I got half way through chapter 5 and decided I needed to try a new book.
I read this book twice.The book does so using practical examples and emphasizing approaches that represent how the language should truly be used today. You may have heard of the MVC Model. On the one hand, this approach does exclude a decent percentage of Web users and some browsers that would otherwise be deemed modern. Some of the operators in Table 4. In order to be able to perform live testing of your site in multiple browsers.
PreCedenCe oPerator note 1. For one. You can even declare multiple variables at the same time while simultaneously assigning values: