Traditionally in browsers the HTML parser has run on the main thread and has blocked after a </script> tag until the script has been retrieved from the network and executed. The HTML parser in Firefox 4 and later supports speculative parsing off the main thread. It parses ahead while scripts are being downloaded and executed. As in Firefox 3.5 and 3.6, the HTML parser starts speculative loads for scripts, style sheets and images it finds ahead in the stream. However, in Firefox 4 and later the HTML parser also runs the HTML tree construction algorithm speculatively. The upside is that when a speculation succeeds, there's no need to reparse the part of the incoming file that was already scanned for scripts, style sheets and images. The downside is that there's more work lost when the speculation fails.
Logs the number of times that this particular call to count() has been called. This function takes an optional argument label.
Displays an interactive tree of the descendant elements of the specified XML/HTML element. If it is not possible to display as an element the JavaScript Object view is shown instead. The output is presented as a hierarchical listing of expandable nodes that let you see the contents of child nodes.
Creates a new inline group in the Web Console log. This indents all following output by an additional level, until console.groupEnd() is called.
Outputs an informational message to the Web Console. In Firefox and Chrome, a small "i" icon is displayed next to these items in the Web Console's log.
Starts a timer you can use to track how long an operation takes. You give each timer a unique name, and may have up to 10,000 timers running on a given page. When you call console.timeEnd() with the same name, the browser will output the time, in milliseconds, that elapsed since the timer was started.
Adds a single marker to the browser's Timeline or Waterfall tool. This lets you correlate a point in your code with the other events recorded in the timeline, such as layout and paint events.
Writes an error message to the console if the assertion is false. If the assertion is true, nothing happens.
Displays an interactive list of the properties of the specified JavaScript object. The output is presented as a hierarchical listing with disclosure triangles that let you see the contents of child objects.
Creates a new inline group in the Web Console. Unlike console.group(), however, the new group is created collapsed. The user will need to use the disclosure button next to it to expand it, revealing the entries created in the group.
Stops a timer that was previously started by calling console.time().
The DataTransfer object is used to hold the data that is being dragged during a drag and drop operation. It may hold one or more data items, each of one or more data types. For more information about drag and drop, see HTML Drag and Drop API.