astro-build-time-constants/README.md

Astro integration to define build-time constants: dates, custom properties,...

# astro-build-time-constants

This Astro integration generates the file ```src/astro-build-time-constants.ts```,
which contains constants related to build time, typically:

```ts
export const digits2 = (number: number) => number < 10 ? '0' + number : '' + number
export const astroBuildTimeConstants = {
  internal: {
    epoch: 1758444256,
    seconds: 15,
    minutes: 44,
    hours: 10,
    fullYear: 2025,
    month: 9,
    date: 21,
    iso: "2025-09-21T08:44:15.899Z",
  },
  custom: {
    "myParam": "myValue",
    "myObject": {
      "myValue": 10
    }
  },
}
```

Internal objects contains built-in constants, such as the build date.

Custom object is the object passed as a parameter of ```buildTimeConstants()```
when initializing the integration in ```astro.config.mjs```. This ease usage
of custom configuration parameters

Usage in an astro components is then typically

```jsx
---

import { astroBuildTimeConstants } from '../astro-build-time-constants'
---

<p>
  Built on {astroBuildTimeConstants.internal.iso}
</p>
<p>
  My parameter is {astroBuildTimeConstants.custom.myParam}
</p>
```

## Installation

### Quick install

To install astro-build-time-constants, run the following from your project directory and follow the prompts:

```bash
npx astro add astro-build-time-constants
```

### Manual install

First, install the astro-build-time-constants package using your package manager. If you're using npm, run this in the terminal:

```bash
npm install astro-build-time-constants
```

Then, apply this integration to your ```astro.config.mjs``` file using the integrations property:

```js
import { defineConfig } from 'astro/config';
import buildTimeConstants from 'astro-build-time-constants'

export default defineConfig({
  integrations: [
    buildTimeConstants()
  ],
});
```


# Adding custom properties

Custom properties can be added as the ```buildTimeConstants()``` arguments, such as
```js
export default defineConfig({
  ...
  integrations: [
    ...
    buildTimeConstants( {
      myParam: "myValue",
      myObject: {
        myValue: 10,
      }
    }),
    ...
  ]
});

```