# cleanup-attrs — Remove Redundant SVG Attributes

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_(no submodules)_
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## Purpose

`cleanupAttrs` strips attributes whose values match the SVG specification defaults and trims whitespace from all remaining attribute values. Many SVG authoring tools emit default attribute values explicitly (e.g. `fill="black"`, `opacity="1"`) that carry no information. Removing them reduces file size without changing the rendered output.

## Features

- Removes attributes whose trimmed value matches the SVG default (sourced from `DEFAULT_ATTRS` in constants)
- Removes attributes with empty string values after trimming
- Trims leading/trailing whitespace from all attribute values
- Passes non-element nodes through unchanged
- Included in `PRESET_DEFAULT`, `PRESET_SAFE`, and `PRESET_AGGRESSIVE`

## Usage: Basic Example

```typescript
import { compressSvg } from '@suaveplan/compress-svg';
import { cleanupAttrs } from '@suaveplan/compress-svg/plugins/cleanup-attrs';

const svg = '<svg><rect fill="black" opacity="1" x="10" fill-opacity="1"/></svg>';
const result = compressSvg(svg, { plugins: [cleanupAttrs] });
// result.data === '<svg><rect x="10"/></svg>'
```

## Usage: Advanced Example

```typescript
import { cleanupAttrs } from '@suaveplan/compress-svg/plugins/cleanup-attrs';

const node = {
  type: 'element' as const,
  name: 'rect',
  attributes: { fill: 'red', opacity: '1', style: '', x: '  10  ' },
  children: [],
};
const result = cleanupAttrs.apply(node, { floatPrecision: 3, transformPrecision: 5 });
// result.attributes === { fill: 'red', x: '10' }
// opacity removed (default), style removed (empty), x trimmed
```

## API Reference

### `cleanupAttrs: SvgPlugin`

| Property | Value |
|----------|-------|
| `name`   | `"cleanupAttrs"` |
| `apply`  | `(node, options) => SvgNode \| null` |

Iterates over each attribute:

1. Trims the value.
2. Drops the attribute if the trimmed value is empty.
3. Drops the attribute if `DEFAULT_ATTRS[key] === trimmedValue`.
4. Otherwise keeps the attribute with the trimmed value.

**Returns the node unchanged** for non-element nodes.

**Default attributes removed** (partial list): `fill="black"`, `fill-opacity="1"`, `stroke-opacity="1"`, `opacity="1"`, `display="inline"`, `visibility="visible"`, `overflow="visible"`.

## Implementation Notes

The `DEFAULT_ATTRS` constant is defined centrally in `src/constants/index.ts` so all plugins share the same definition. The plugin always returns a new node object with a fresh `attributes` record, even if no attributes were removed — callers should not rely on reference equality after the plugin runs. Only exact-string matches against the default values are checked; no numeric normalisation is performed (e.g. `opacity="1.0"` is not recognised as a default).