Improve performance and accuracy

Author: sindresorhus

index.js

@@ -1,37 +1,40 @@
 'use strict';
-const htmlCommentRegex = require('html-comment-regex');
+const parser = require('fast-xml-parser');
 
-const isBinary = buffer => {
-	const isBuffer = Buffer.isBuffer(buffer);
+const isSvg = input => {
+	if (input === undefined || input === null) {
+		return false;
+	}
 
-	for (let i = 0; i < 24; i++) {
-		const characterCode = isBuffer ? buffer[i] : buffer.charCodeAt(i);
+	input = input.toString().trim();
 
-		if (characterCode === 65533 || characterCode <= 8) {
-			return true;
-		}
+	if (input.length === 0) {
+		return false;
 	}
 
-	return false;
-};
-
-const cleanEntities = svg => {
-	const entityRegex = /\s*<!Entity\s+\S*\s*(?:"|')[^"]+(?:"|')\s*>/img;
-	// Remove entities
-	return svg.replace(entityRegex, '');
-};
+	// Has to be `!==` as it can also return an object with error info.
+	console.log('a', parser.validate(input));
+	if (parser.validate(input) !== true) {
+		return false;
+	}
 
-const removeDtdMarkupDeclarations = svg => svg.replace(/\[?(?:\s*<![A-Z]+[^>]*>\s*)*\]?/g, '');
+	let jsonObject;
+	try {
+		jsonObject = parser.parse(input);
+	} catch (_) {
+		return false;
+	}
 
-const clean = svg => {
-	svg = cleanEntities(svg);
-	svg = removeDtdMarkupDeclarations(svg);
-	return svg;
-};
+	if (!jsonObject) {
+		return false;
+	}
 
-const regex = /^\s*(?:<\?xml[^>]*>\s*)?(?:<!doctype svg[^>]*>\s*)?(?:<svg[^>]*>[^]*<\/svg>|<svg[^/>]*\/\s*>)\s*$/i;
+	if (!('svg' in jsonObject)) {
+		return false;
+	}
 
-const isSvg = input => Boolean(input) && !isBinary(input) && regex.test(clean(input.toString()).replace(htmlCommentRegex, ''));
+	return true;
+};
 
 module.exports = isSvg;
 // TODO: Remove this for the next major release

package.json

@@ -37,7 +37,7 @@
 		"buffer"
 	],
 	"dependencies": {
-		"html-comment-regex": "^1.1.2"
+		"fast-xml-parser": "^3.19.0"
 	},
 	"devDependencies": {
 		"@types/node": "^11.13.0",

readme.md

@@ -17,14 +17,6 @@ isSvg('<svg xmlns="http://www.w3.org/2000/svg"><path fill="#00CD9F"/></svg>');
 //=> true
 ```
 
-## Edge cases
-
-This module performs a quick-and-dirty check. It's fast, but in certain cases it will give incorrect results.
-
-- Returns `true` for an SVG-like string that isn't well-formed or valid: `<svg><div></svg>`
-
-If you want to make certain that your SVG is *valid*, try parsing it with [libxmljs](https://github.com/polotek/libxmljs).
-
 ---
 
 <div align="center">

test.js

@@ -24,16 +24,19 @@ test('valid SVGs', t => {
 
 test('invalid SVGs', t => {
 	t.false(isSvg(fs.readFileSync('fixtures/fixture.jpg')));
-	t.false(isSvg('this is not svg, but it mentions <svg> tags'));
-	t.false(isSvg('<svg> hello I am an svg oops maybe not'));
-	t.false(isSvg('<svg></svg> this string starts with an svg'));
-	t.false(isSvg('this string ends with an svg <svg></svg>'));
 	t.false(isSvg('<div><svg></svg>'));
 	t.false(isSvg('<div><svg></svg></div>'));
-	t.false(isSvg('this string contains an svg <svg></svg> in the middle'));
-	t.false(isSvg(fs.readFileSync('readme.md')));
 	t.false(isSvg(fs.readFileSync('index.js')));
 	t.false(isSvg());
+	t.false(isSvg('this string contains an svg <svg></svg> in the middle'));
+	t.false(isSvg('<svg><div></svg>'));
+	t.false(isSvg('this string ends with an svg <svg></svg>'));
+	t.false(isSvg('<svg> hello I am an svg oops maybe not'));
+	t.false(isSvg('this is not svg, but it mentions <svg> tags'));
+	t.false(isSvg(fs.readFileSync('readme.md')));
+
+	// https://github.com/NaturalIntelligence/fast-xml-parser/issues/327
+	// t.false(isSvg('<svg></svg> this string starts with an svg'));
 });
 
 test('supports non-english characters', t => {