forked from lix-project/lix-website
64 lines
1.4 KiB
Markdown
64 lines
1.4 KiB
Markdown
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# undefsafe
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Simple *function* for retrieving deep object properties without getting "Cannot read property 'X' of undefined"
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Can also be used to safely set deep values.
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## Usage
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```js
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var object = {
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a: {
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b: {
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c: 1,
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d: [1,2,3],
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e: 'remy'
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}
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}
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};
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console.log(undefsafe(object, 'a.b.e')); // "remy"
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console.log(undefsafe(object, 'a.b.not.found')); // undefined
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```
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Demo: [https://jsbin.com/eroqame/3/edit?js,console](https://jsbin.com/eroqame/3/edit?js,console)
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## Setting
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```js
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var object = {
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a: {
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b: [1,2,3]
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}
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};
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// modified object
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var res = undefsafe(object, 'a.b.0', 10);
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console.log(object); // { a: { b: [10, 2, 3] } }
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console.log(res); // 1 - previous value
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```
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## Star rules in paths
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As of 1.2.0, `undefsafe` supports a `*` in the path if you want to search all of the properties (or array elements) for a particular element.
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The function will only return a single result, either the 3rd argument validation value, or the first positive match. For example, the following github data:
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```js
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const githubData = {
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commits: [{
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modified: [
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"one",
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"two"
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]
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}, /* ... */ ]
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};
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// first modified file found in the first commit
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console.log(undefsafe(githubData, 'commits.*.modified.0'));
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// returns `two` or undefined if not found
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console.log(undefsafe(githubData, 'commits.*.modified.*', 'two'));
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```
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