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181 lines
4.8 KiB
Markdown
181 lines
4.8 KiB
Markdown
---
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language: haml
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filename: learnhaml.haml
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contributors:
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- ["Simon Neveu", "https://github.com/sneveu"]
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---
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Haml is a markup language predominantly used with Ruby that cleanly and simply describes the HTML of any web document without the use of inline code. It is a popular alternative to using Rails templating language (.erb) and allows you to embed Ruby code into your markup.
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It aims to reduce repetition in your markup by closing tags for you based on the structure of the indents in your code. The result is markup that is well-structured, DRY, logical, and easier to read.
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You can also use Haml on a project independent of Ruby, by installing the Haml gem on your machine and using the command line to convert it to html.
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$ haml input_file.haml output_file.html
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```haml
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/ -------------------------------------------
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/ Indenting
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/ -------------------------------------------
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/
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Because of the importance indentation has on how your code is rendered, the
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indents should be consistent throughout the document. Any differences in
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indentation will throw an error. It's common-practice to use two spaces,
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but it's really up to you, as long as they're constant.
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/ -------------------------------------------
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/ Comments
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/ -------------------------------------------
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/ This is what a comment looks like in Haml.
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/
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To write a multi line comment, indent your commented code to be
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wrapped by the forward slash
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-# This is a silent comment, which means it wont be rendered into the doc at all
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/ -------------------------------------------
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/ Html elements
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/ -------------------------------------------
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/ To write your tags, use the percent sign followed by the name of the tag
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%body
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%header
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%nav
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/ Notice no closing tags. The above code would output
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<body>
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<header>
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<nav></nav>
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</header>
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</body>
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/ The div tag is the default element, so they can be written simply like this
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.foo
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/ To add content to a tag, add the text directly after the declaration
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%h1 Headline copy
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/ To write multiline content, nest it instead
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%p
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This is a lot of content that we could probably split onto two
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separate lines.
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/
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You can escape html by using the ampersand and equals sign ( &= ). This
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converts html-sensitive characters (&, /, :) into their html encoded
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equivalents. For example
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%p
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&= "Yes & yes"
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/ would output 'Yes & yes'
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/ You can unescape html by using the bang and equals sign ( != )
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%p
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!= "This is how you write a paragraph tag <p></p>"
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/ which would output 'This is how you write a paragraph tag <p></p>'
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/ CSS classes can be added to your tags either by chaining .classnames to the tag
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%div.foo.bar
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/ or as part of a Ruby hash
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%div{:class => 'foo bar'}
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/ Attributes for any tag can be added in the hash
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%a{:href => '#', :class => 'bar', :title => 'Bar'}
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/ For boolean attributes assign the value 'true'
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%input{:selected => true}
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/ To write data-attributes, use the :data key with its value as another hash
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%div{:data => {:attribute => 'foo'}}
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/ -------------------------------------------
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/ Inserting Ruby
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/ -------------------------------------------
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/
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To output a Ruby value as the contents of a tag, use an equals sign followed
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by the Ruby code
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%h1= book.name
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%p
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= book.author
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= book.publisher
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/ To run some Ruby code without rendering it to the html, use a hyphen instead
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- books = ['book 1', 'book 2', 'book 3']
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/ Allowing you to do all sorts of awesome, like Ruby blocks
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- books.shuffle.each_with_index do |book, index|
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%h1= book
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if book do
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%p This is a book
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/ Adding ordered / unordered list
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%ul
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%li
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=item1
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=item2
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/
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Again, no need to add the closing tags to the block, even for the Ruby.
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Indentation will take care of that for you.
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/ -------------------------------------------
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/ Inserting Table with bootstrap classes
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/ -------------------------------------------
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%table.table.table-hover
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%thead
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%tr
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%th Header 1
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%th Header 2
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%tr
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%td Value1
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%td value2
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%tfoot
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%tr
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%td
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Foot value
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/ -------------------------------------------
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/ Inline Ruby / Ruby interpolation
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/ -------------------------------------------
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/ Include a Ruby variable in a line of plain text using #{}
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%p Your highest scoring game is #{best_game}
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/ -------------------------------------------
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/ Filters
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/ -------------------------------------------
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/
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Use the colon to define Haml filters, one example of a filter you can
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use is :javascript, which can be used for writing inline js
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:javascript
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console.log('This is inline <script>');
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```
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## Additional resources
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- [What is HAML?](http://haml.info/) - A good introduction that does a much better job of explaining the benefits of using HAML.
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- [Official Docs](http://haml.info/docs/yardoc/file.REFERENCE.html) - If you'd like to go a little deeper.
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