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* Replace tiny bitmaps with base64-encoded URIs
* Optimize SVGs; replace logo PNG with SVG
* Modernize favicon
* Embed CSS; a bit unorthodox, but we’re a single page so there’s no point in separate .css files and their separate HTTP requests
* Documentation is now markdown, converted to HTML on compilation
* Render the examples when we’re rendering index.html; they compile so quickly that there’s no need to pre-render them and save the intermediate .js files
* Split apart index.html into components that Cakefile assembles, so that we can add in logic to include different files for v1 versus v2
* Split building index.html and building test.html into two tasks; collapse the parts of `releaseHeader` into one compact function
* Move include logic into templates
* Get error messages tests to work in the browser
* Update output index.html
* Split body into nav and body
* Watch subtemplates
* Revert "Split body into nav and body"
This reverts commit ec9e559ec0.
* Add marked
* Update gitignore
* Use idiomatic markdown output for code blocks (<pre><code>)
* Handle ids within the template, not in the Cakefile; remove marked’s auto-generated and conflicting ids
* Move the `codeFor` function into versioned folders, so that v1 and v2 docs can have different example code blocks/editors
* Update packages, including new highlight.js which supports our newer keywords and triple backticks (docs output is unchanged)
18 lines
1.1 KiB
Markdown
18 lines
1.1 KiB
Markdown
## The Existential Operator
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It’s a little difficult to check for the existence of a variable in JavaScript. `if (variable) …` comes close, but fails for zero, the empty string, and false. CoffeeScript’s existential operator `?` returns true unless a variable is **null** or **undefined**, which makes it analogous to Ruby’s `nil?`
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It can also be used for safer conditional assignment than `||=` provides, for cases where you may be handling numbers or strings.
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```
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codeFor('existence', 'footprints')
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```
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The accessor variant of the existential operator `?.` can be used to soak up null references in a chain of properties. Use it instead of the dot accessor `.` in cases where the base value may be **null** or **undefined**. If all of the properties exist then you’ll get the expected result, if the chain is broken, **undefined** is returned instead of the **TypeError** that would be raised otherwise.
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```
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codeFor('soaks')
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```
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Soaking up nulls is similar to Ruby’s [andand gem](https://rubygems.org/gems/andand), and to the [safe navigation operator](http://docs.groovy-lang.org/latest/html/documentation/index.html#_safe_navigation_operator) in Groovy.
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