Save the document 7 Look at the document in your browser in .NET framework

Maker GTIN - 12 in .NET framework Save the document 7 Look at the document in your browser

The browser displays either a list of plug-ins or the No Plug-ins message The script in this example demonstrates one way to work with objects that can have any number of entries In this case, a client can have more than one plug-in installed The plug-in information appears in a collection Think of a collection as a box that contains any number of similar items All the items are of the same type, but they contain unique content A baseball card collection consists of baseball cards, but it s unlikely that every card will have information about the same player JavaScript looks at collections as arrays An array is a single memory structure grouping many values, where each value can be accessed using the same variable name, but with a number, called an index, singling out that particular value from the group Arrays work much like apartments in a building Every apartment has the same address So, to look for John Smith you begin by looking for the building After you find the building (the name of the array), you look for John Smith s apartment The windowclientInformationplugins[Counter]) entry performs the same task as locating a particular apartment It tells JavaScript to look for a particular item in the plugins array, which is actually a collection Notice how the code also uses the windowclientInformationpluginslength property in two different ways The first use is to determine whether there are any plug-ins A length of 0 in a collection means there are

no items in the collection, or no plug-ins in this case The second is to determine how many plug-ins to process as part of the for loop

One of the most important scripting tasks is associating a function with an event You have access to a number of events for just about every object that a browser can access (I can t think of an object that doesn t include events, but I m sure there must be one) Generally, the choice of which event to use is relatively easy to figure out For example, you use the onclick event when you want to track the user s clicks on a particular object and most user interface objects support this event The first control that developers work with, in most cases, is a pushbutton and the most common event handled by functions for pushbuttons is onclick

Whenever you create a function, it s important to plan thoroughly before you actually write any code The world is filled with bad code written because someone got very excited about doing something and didn t fully outline what it was they wanted to do Because many functions replicate tasks you want to do, it pays to write the steps down as you would do them For example, when you want to add two numbers, you follow these steps:

1 Discover the value of the first number 2 Discover the value of the second number 3 Add the two numbers together 4 Look at the result

A function works the same way You need to obtain two numbers from somewhere normally a form containing two text boxes JavaScript adds the two numbers together It then places the result in a third text box, where the user looks at the result The process JavaScript uses is the same as the process you use The only difference is that you don t have to perform the work you let JavaScript do the work for you There s one missing piece: Something has to tell JavaScript to perform the addition Generally, the developer creates an Add pushbutton and associates the onclick event with the function that actually performs the task The following steps show how to create the required code: