File download attribute in knockout

You can use whatever mechanism is a convenient fit for your chosen server-side technology. You can fetch data from the server:. So, all Knockout needs to help you do is:. To make it easy to serialize view model data, including observables and the like, Knockout includes two helper functions:. The download attribute specifies that the target the file specified in the href attribute will be downloaded when a user clicks on the hyperlink.

The optional value of the download attribute will be the new name of the file after it is downloaded. There are no restrictions on allowed values, and the browser will automatically detect the correct file extension and add it to the file.

Specify a value for the download attribute, which will be the new filename of the downloaded file "w3logo. Podcast Who is building clouds for the independent developer? Exploding turkeys and how not to thaw your frozen bird: Top turkey questions Featured on Meta.

Now live: A fully responsive profile. Reducing the weight of our footer. Related Hot Network Questions. Question feed. Stack Overflow works best with JavaScript enabled. I recommend referencing this file when learning Knockout and when debugging.

Knockout is best explained by first examining how you would write code to push data from a source object to HTML elements without using Knockout the relevant source code can be found in sample page without-knockout. If you have an object from which you want to push data into standard HTML elements, you could use jQuery:.

This code sample uses jQuery to locate the HTML elements with the corresponding IDs and sets their values to each appropriate object property. There are three main points to notice in this code. First, the values are pushed from the source object into the HTML elements, thus requiring a line of code for each mapping from source value to target element.

If there were many more properties or if there were arrays and object graphs , the code could easily get unwieldy. Notice the id attributes have been replaced with data-bind attributes.

This sets the data context for the page to the product object, which means that the target elements can then identify the property of that data context to which they want to bind:.

The values in the source object will be pushed to the target elements in this page. The linkage between the target elements and the source object is defined by the data-bind attribute.

In the preceding example, Knockout sees the data-bind attribute for the first span tag is identifying that its text value should be bound to the itemNumber property. Knockout then pushes the value for the product. You can see how using Knockout could easily reduce code. As the number of properties and elements increase, the only JavaScript code required is the applyBindings function. For this, we need observables.

Knockout adds dependency tracking through observables, which are objects that can notify listeners when underlying values have changed this is similar to the concept of the INotifyPropertyChanged interface in XAML technology.

Knockout implements observable properties by wrapping object properties with a custom function named observable. For example, instead of setting a property in an object like so:.

Once the properties are defined as observables, the data binding really takes shape. The first object data. The first and second div tags contain HTML elements bound to non-observable properties.