Add loop metadata.

[cossssmin]

Proposed Changes

This PR adds functionality that exposes some information about the loop currently being executed.

A loop object is constructed and passed into the locals of the loop being executed.

Inside a loop, you now have access to the following variables:

• loop.index - the current iteration of the loop (0 indexed)
• loop.remaining - number of iterations until the end (0 indexed)
• loop.first - boolean indicating if it's the first iteration
• loop.last - boolean indicating if it's the last iteration
• loop.length - total number of items

Usage

<each loop='item in items'>
  <li>Item value: {{ item }}</li>
  <li>Current iteration of the loop: {{ loop.index }}</li>
  <li>Number of iterations until the end: {{ loop.remaining }}</li>
  <li>This {{ loop.first ? 'is' : 'is not' }} the first iteration</li>
  <li>This {{ loop.last ? 'is' : 'is not' }} the last iteration</li>
  <li>Total number of items: {{ loop.length }}</li>
</each>

Nested loops

The loop object contains information about the current loop.

This means you can't access the loop.remaining variable of the parent loop.

A possible solution, though outside the scope of this PR, would be for the <each> tag to accept a locals="" attribute, which could be used to pass down data - in this case, the parent loop's metadata.

Types of Changes

• [ ] Bug (non-breaking change which fixes an issue)
• [x] Feature (non-breaking change which adds functionality)
• [ ] Breaking Change (fix or feature which changes existing functionality)

Checklist

• [x] I have read the CONTRIBUTING guide
• [x] Lint and unit tests pass with my changes
• [x] I have added tests that prove my fix is effective/works
• [x] I have added necessary documentation (if appropriate)
• [x] Any dependent changes are merged and published in downstream modules

---

If merged, this PR closes #65

[coveralls]

Coverage increased (+0.07%) to 97.423% when pulling 3cff5cbfcdcd3a048061feb47ff0f0a8e0f4f3d7 on cossssmin:loop-meta into e99bb12a3f68d8bff6b559117350e758fb9e0aa0 on posthtml:master.

[cossssmin]

Extracted to a getLoopMeta function where I check what we're iterating over and compute the object with loop metadata accordingly. Please check and let me know what you think.

[cossssmin]

Forgot to add docs, doing it now!

[Scrum]

publish v1.3.0