[refactor] refactor trim utils and write tests (#6909)

src/compiler/utils/patterns.ts

@@ -1,3 +1,5 @@
 export const whitespace = /[ \t\r\n]/;
+export const start_whitespace = /^[ \t\r\n]*/;
+export const end_whitespace = /[ \t\r\n]*$/;
 
 export const dimensions = /^(?:offset|client)(?:Width|Height)$/;

src/compiler/utils/trim.ts

@@ -1,15 +1,9 @@
-import { whitespace } from './patterns';
+import { start_whitespace, end_whitespace } from './patterns';
 
 export function trim_start(str: string) {
-	let i = 0;
-	while (whitespace.test(str[i])) i += 1;
-
-	return str.slice(i);
+	return str.replace(start_whitespace, '');
 }
 
 export function trim_end(str: string) {
-	let i = str.length;
-	while (whitespace.test(str[i - 1])) i -= 1;
-
-	return str.slice(0, i);
+	return str.replace(end_whitespace, '');
 }

test/utils/index.ts

@@ -0,0 +1,16 @@
+import * as assert from 'assert';
+import { trim_start, trim_end } from '../../src/compiler/utils/trim';
+
+describe('utils', () => {
+	describe('trim', () => {
+		it('trim_start', () => {
+			const value = trim_start('	\r\n\t svelte content \r\n\t	');
+			assert.equal(value, 'svelte content \r\n\t	');
+		});
+
+		it('trim_end', () => {
+			const value = trim_end('	\r\n\t svelte content \r\n\t	');
+			assert.equal(value, '	\r\n\t svelte content');
+		});
+	});
+});