45 lines
1.1 KiB
Markdown
45 lines
1.1 KiB
Markdown
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# Functions
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<a id="assert"></a>
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## assert
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▸ **assert**<`T`>(test: *`Falsy` | `T`*, message: *`string` | `MessageFn`*, code?: *`number`*, data?: *`any`*): `boolean`
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*Defined in [assert.ts:28](https://github.com/polkadot-js/common/blob/8513530/packages/util/src/assert.ts#L28)*
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*__name__*: assert
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*__summary__*: Checks for a valid test, if not ExtError is thrown.
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*__description__*: Checks that `test` is a truthy value. If value is falsy (`null`, `undefined`, `false`, ...), it throws an ExtError with the supplied `message` and an optional `code` and `data`. When `test` passes, `true` is returned.
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*__example__*:
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```javascript
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const { assert } from '@polkadot/util';
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assert(true, 'True should be true'); // true returned
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assert(false, 'False should not be true'); // ExtError thrown
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assert(false, () => 'message'); // ExtError with 'message'
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```
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**Type parameters:**
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#### T
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**Parameters:**
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| Name | Type | Default value |
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| ------ | ------ | ------ |
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| test | `Falsy` | `T` | - |
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| message | `string` | `MessageFn` | - |
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| `Default value` code | `number` | ExtError.CODES.ASSERT |
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| `Optional` data | `any` | - |
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**Returns:** `boolean`
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___
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