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37 lines
682 B
Markdown
37 lines
682 B
Markdown
---
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date: 20201103
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id: eb8253f8-f376-4b73-9098-35da64a5a6e7
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title: Destructuring Default Values
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---
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# Basic syntax
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``` javascript
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const [x=3, y] = []
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console.log(x, y) // 3 undefined
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```
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# Computed on demand
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Default values are computed when they are needed:
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``` javascript
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function tralala() {
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return "tralala string"
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}
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const {computed=tralala()} = {}
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console.log(computed) // tralala string
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```
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# Refer to other variables
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Default value an refer to other
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[variables](20200613170532-variable_types_in_javascript) in the same
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pattern:
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``` javascript
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const [x=3, y=x] = []; // x=3; y=3
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const [i=3, j=x] = [7]; // i=7; j=7
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const [k=3, l=x] = [7, 2]; // k=7; l=2
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```
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