The command queue¶
Almost everything you can do with the Web SDK from the browser/webpage can
be done with the orb() command queue. This guide explains what this is, how
it works, and how to use it.
The orb command queue¶
The JavaScript tracking snippet defines a global orb() function known as the
"command queue". It is named this because rather than executing commands
immediately (like calling a function), it adds them to a queue and will
execute them once the tms.js bootloader is fully loaded.
The tracking snippet defines within the orb() function (which is also an
object in JavaScript) a property q as an empty array. Prior to the bootloader
loading, calling the orb() function appends the q array with the command.
For example, if you were to run the tracking snippet, run a single command, and
then print out the contents of the orb.q variable immediately, you'd see an
array, containing the command you just passed to the orb() function:
// We assume the installation snippet has already ran
orb('config', 'SCRIPT_TOKEN_1', { namespace: 'namespace1' });
console.log(orb.q);
// Outputs the following:
// [
// ['config', 'SCRIPT_TOKEN_1', { namespace: 'namespace1' }]
// ]
Once the bootloader is loaded, it inspects the contents of orb.q and executes
each command in order. After that, the orb() function is redefined, so all
subsequent calls execute immediately. This pattern abstracts away most of the
complexities of asynchronous code!
Adding commands to the queue¶
All calls to the orb() command queue share a common signature. The first
parameter, the "command", is a string that identifies a particular bootloader
method. The next parameter identifies the target or object of worth for that
command. The last parameter is an object, which contains any other required
parameters that the command might need.
All commands are global and are run by the bootloader. For a comprehensive list
of all commands that can be executed via the command queue, see the
bootloader section of the Web SDK Reference.
Info
Once the bootloader has loaded, all commands are also available as
functions under the loaded orb.bootloader object. orb('config', ...)
can also be called with orb.bootloader.config(...).