UTF8-BOM - if input string has BOM that mean output string also should have it (#3283)

The issue that prettier lost BOM and mean convert UTF-8 with BOM to just UTF-8

index.js

@@ -1,6 +1,5 @@
 "use strict";
 
-const stripBom = require("strip-bom");
 const comments = require("./src/comments");
 const version = require("./package.json").version;
 const printAstToDoc = require("./src/printer").printAstToDoc;
@@ -68,7 +67,11 @@ function formatWithCursor(text, opts, addAlignmentSize) {
     return { formatted: text };
   }
 
-  text = stripBom(text);
+  const UTF8BOM = 0xfeff;
+  const hasUnicodeBOM = text.charCodeAt(0) === UTF8BOM;
+  if (hasUnicodeBOM) {
+    text = text.substring(1);
+  }
 
   if (
     opts.insertPragma &&
@@ -110,7 +113,10 @@ function formatWithCursor(text, opts, addAlignmentSize) {
   const doc = printAstToDoc(ast, opts, addAlignmentSize);
   opts.newLine = guessLineEnding(text);
   const toStringResult = printDocToString(doc, opts);
-  const str = toStringResult.formatted;
+  let str = toStringResult.formatted;
+  if (hasUnicodeBOM) {
+    str = String.fromCharCode(UTF8BOM) + str;
+  }
   const cursorOffsetResult = toStringResult.cursor;
   ensureAllCommentsPrinted(astComments);
   // Remove extra leading indentation as well as the added indentation after last newline

package.json

@@ -46,7 +46,6 @@
     "remark-parse": "4.0.0",
     "semver": "5.4.1",
     "string-width": "2.1.1",
-    "strip-bom": "3.0.0",
     "typescript": "2.5.3",
     "typescript-eslint-parser": "git://github.com/eslint/typescript-eslint-parser.git#9c71a627da36e97da52ed2731d58509c952b67ae",
     "unicode-regex": "1.0.1",

tests/css_bom/__snapshots__/jsfmt.spec.js.snap

@@ -10,7 +10,7 @@ html {
 
 }
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-/* Block comment */
+/* Block comment */
 
 html {
   content: "#{1}";

tests/typescript/compiler/__snapshots__/jsfmt.spec.js.snap

@@ -74,7 +74,7 @@ var b = (<any>new a);
 var b = (<any>new a.b);
 var b = (<any>new a).b
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-class a {
+class a {
   static b: any;
 }
 
@@ -200,7 +200,7 @@ exports[`commentInNamespaceDeclarationWithIdentifierPathName.ts 1`] = `
     function foo() {}
 }
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-namespace hello.hi.world {
+namespace hello.hi.world {
   function foo() {
   }
 }

tests/typescript/conformance/es6/templates/__snapshots__/jsfmt.spec.js.snap

@@ -4,7 +4,7 @@ exports[`templateStringWithEmbeddedTypeAssertionOnAdditionES6.ts 1`] = `
 // @target: ES6
 var x = \`abc\${ <any>(10 + 10) }def\`;
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-// @target: ES6
+// @target: ES6
 var x = \`abc\${<any>(10 + 10)}def\`;
 
 `;

tests/typescript/conformance/types/tuple/__snapshots__/jsfmt.spec.js.snap

@@ -27,7 +27,7 @@ unionTuple = unionTuple2;
 unionTuple2 = unionTuple;
 numStrTuple = unionTuple3;
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-// no error
+// no error
 var numStrTuple: [number, string] = [5, "hello"];
 var numStrTuple2: [number, string] = [5, "foo", true];
 var numStrBoolTuple: [number, string, boolean] = [5, "foo", true];
@@ -89,7 +89,7 @@ var eleUnion24 = unionTuple2[idx1]; // string | number | boolean
 var eleUnion25 = unionTuple2["0"]; // boolean
 var eleUnion26 = unionTuple2["1"]; // string | number
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-var strNumTuple: [string, number] = ["foo", 10];
+var strNumTuple: [string, number] = ["foo", 10];
 var numTupleTuple: [number, [string, number]] = [10, ["bar", 20]];
 var unionTuple1: [number, string | number] = [10, "foo"];
 var unionTuple2: [boolean, string | number] = [true, "foo"];
@@ -178,7 +178,7 @@ var zipResultEle = zipResult[0]; // [string, number]
 var zipResultEleEle = zipResult[0][0]; // string
 
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-function combine<T, U>(x: T, y: U): [T, U] {
+function combine<T, U>(x: T, y: U): [T, U] {
   return [x, y];
 }
 

tests/typescript/conformance/types/union/__snapshots__/jsfmt.spec.js.snap

@@ -76,7 +76,7 @@ var unionWithRestParameter4: { (...a: string[]): string; } | { (a: string, b: st
 strOrNum = unionWithRestParameter4("hello"); // error supplied parameters do not match any call signature
 strOrNum = unionWithRestParameter4("hello", "world");
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-var numOrDate: number | Date;
+var numOrDate: number | Date;
 var strOrBoolean: string | boolean;
 var strOrNum: string | number;
 
@@ -188,7 +188,7 @@ var fUnion: typeof f1 | typeof f2 | typeof f3 | typeof f4 | typeof f5 | typeof f
 
 fUnion(""); // All constituents can be called by passing a single string.
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-function f1(s: string) {}
+function f1(s: string) {}
 function f2(s?: string) {}
 function f3(...s: string[]) {}
 function f4(s: string, s2?: string) {}
@@ -236,7 +236,7 @@ f12345("a");  // error
 f12345("a", "b");
 f12345("a", "b", "c");  // error
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-type F1 = (a: string, b?: string) => void;
+type F1 = (a: string, b?: string) => void;
 type F2 = (a: string, b?: string, c?: string) => void;
 type F3 = (a: string, ...rest: string[]) => void;
 type F4 = (a: string, b?: string, ...rest: string[]) => void;
@@ -336,7 +336,7 @@ strOrNum = new unionWithRestParameter3('hello', 10, 11); // error no call signat
 strOrNum = new unionWithRestParameter3('hello', "hello"); // error no call signature
 strOrNum = new unionWithRestParameter3(); // error no call signature
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-var numOrDate: number | Date;
+var numOrDate: number | Date;
 var strOrBoolean: string | boolean;
 var strOrNum: string | number;
 
@@ -451,7 +451,7 @@ var BC : number | boolean;
 var z1: typeof AB | boolean;
 var z1: string | typeof BC;
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-// A | B is equivalent to A if B is a subtype of A
+// A | B is equivalent to A if B is a subtype of A
 class C {}
 class D extends C {
   foo() {}
@@ -499,7 +499,7 @@ var arr7 = [c, d, e]; // (C | D)[]
 var arr8 = [c, e]; // C[]
 var arr9 = [e, f]; // (E|F)[]
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-// The resulting type an array literal expression is determined as follows:
+// The resulting type an array literal expression is determined as follows:
 // If the array literal is empty, the resulting type is an array type with the element type Undefined.
 // Otherwise, if the array literal is contextually typed by a type that has a property with the numeric name ‘0’, the resulting type is a tuple type constructed from the types of the element expressions.
 // Otherwise, the resulting type is an array type with an element type that is the union of the types of the element expressions.
@@ -558,7 +558,7 @@ var unionOfTypesWithAndWithoutStringSignature1: { [a: number]: number; } | boole
 anyVar = unionOfTypesWithAndWithoutStringSignature1["hello"]; // any
 anyVar = unionOfTypesWithAndWithoutStringSignature1[10]; // any
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-var numOrDate: number | Date;
+var numOrDate: number | Date;
 var anyVar: number;
 
 // If each type in U has a string index signature,