avoid redeclarations of ch and use const

Author: aeschli

src/impl/scanner.ts

@@ -12,8 +12,8 @@ import { ScanError, SyntaxKind, JSONScanner } from '../main';
  */
 export function createScanner(text: string, ignoreTrivia: boolean = false): JSONScanner {
 
+	const len = text.length;
 	let pos = 0,
-		len = text.length,
 		value: string = '',
 		tokenOffset = 0,
 		token: SyntaxKind = SyntaxKind.Unknown,
@@ -109,7 +109,7 @@ export function createScanner(text: string, ignoreTrivia: boolean = false): JSON
 				scanError = ScanError.UnexpectedEndOfString;
 				break;
 			}
-			let ch = text.charCodeAt(pos);
+			const ch = text.charCodeAt(pos);
 			if (ch === CharacterCodes.doubleQuote) {
 				result += text.substring(start, pos);
 				pos++;
@@ -122,8 +122,8 @@ export function createScanner(text: string, ignoreTrivia: boolean = false): JSON
 					scanError = ScanError.UnexpectedEndOfString;
 					break;
 				}
-				ch = text.charCodeAt(pos++);
-				switch (ch) {
+				const ch2 = text.charCodeAt(pos++);
+				switch (ch2) {
 					case CharacterCodes.doubleQuote:
 						result += '\"';
 						break;
@@ -149,9 +149,9 @@ export function createScanner(text: string, ignoreTrivia: boolean = false): JSON
 						result += '\t';
 						break;
 					case CharacterCodes.u:
-						let ch = scanHexDigits(4, true);
-						if (ch >= 0) {
-							result += String.fromCharCode(ch);
+						const ch3 = scanHexDigits(4, true);
+						if (ch3 >= 0) {
+							result += String.fromCharCode(ch3);
 						} else {
 							scanError = ScanError.InvalidUnicode;
 						}
@@ -246,7 +246,7 @@ export function createScanner(text: string, ignoreTrivia: boolean = false): JSON
 
 			// comments
 			case CharacterCodes.slash:
-				let start = pos - 1;
+				const start = pos - 1;
 				// Single-line comment
 				if (text.charCodeAt(pos + 1) === CharacterCodes.slash) {
 					pos += 2;
@@ -266,10 +266,10 @@ export function createScanner(text: string, ignoreTrivia: boolean = false): JSON
 				if (text.charCodeAt(pos + 1) === CharacterCodes.asterisk) {
 					pos += 2;
 
-					let safeLength = len - 1; // For lookahead.
+					const safeLength = len - 1; // For lookahead.
 					let commentClosed = false;
 					while (pos < safeLength) {
-						let ch = text.charCodeAt(pos);
+						const ch = text.charCodeAt(pos);
 
 						if (ch === CharacterCodes.asterisk && text.charCodeAt(pos + 1) === CharacterCodes.slash) {
 							pos += 2;