34fe98f2f2
The example for "without destructuring" was the destructured way it's done in the tutorial, the example for "with destructuring" was the old way to pass in a props object without destructuring
94 lines
2.4 KiB
Markdown
94 lines
2.4 KiB
Markdown
---
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title: A part's draft method
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order: 150
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---
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Time to turn our attention to the draft method of our part.
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Inside our `design/src/bib.js` file, this is what it currently looks like:
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```design/src/bib.mjs
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function draftBib({ part }) {
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return part
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}
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```
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This is an empty skeleton for a draft method. A draft method should always
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return the part object, and that's effectively the only thing it currently
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does.
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## Destructuring the function parameter
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If you're not familiar with the `({ part })` syntax you see above, this is a
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technique called *parameter destructuring* or more generally, [object
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destructuring](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Destructuring_assignment)
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The draft method receives only 1 parameter: An object that holds everything we
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need to draft our method. Destructuring is a way to *pull things out of the
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object into their own variable*. It saves us a bunch of typing as these two are
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equivalent:
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<Tabs tabs="Without destructuring, With destructuring">
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<Tab>
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```design/src/bib.mjs
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function draftBib(props) {
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return props.part
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}
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```
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</Tab>
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<Tab>
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```design/src/bib.mjs
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function draftBib({ part }) {
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return part
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}
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```
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</Tab>
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</Tabs>
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As we'll make our way through this tutorial, we'll need more and more stuff, so
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we'll be pulling it out of the object passed to the draft method via
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*destructuring*.
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<Note>
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If you're new to JavaScript, and don't intuitively _get this_, stick with it. It will become second nature soon enough.
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</Note>
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## Destructuring what we need to start drawing our bib
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Change the function to look like this:
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```design/src/bib.mjs
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function draftBib({
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// highlight-start
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Path,
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Point,
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paths,
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points,
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// highlight-end
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part,
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}) {
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return part
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}
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```
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That's bunch of new lines, but each of one gives us something we'll use in this
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tutorial.
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For a complete list of what you can access via destructuring like this, refer
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to [the draft method reference documentation](/reference/api/part/draft).
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Here's a brief summary of the things we've added above:
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- `Path`: The Path constructor, allows us to create new Paths
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- `Point`: The Point constructor, allows us to create new Points
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- `points`: A container object to hold the part's points
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- `paths`: A container object to hold the part's paths
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Long story short: These will make it possible for us to draw points and paths easily.
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So let's go ahead and do that.
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