--- /dev/null
+/**
+ * @fileoverview Require or disallow Unicode BOM
+ * @author Andrew Johnston <https://github.com/ehjay>
+ */
+"use strict";
+
+//------------------------------------------------------------------------------
+// Rule Definition
+//------------------------------------------------------------------------------
+
+module.exports = {
+ meta: {
+ type: "layout",
+
+ docs: {
+ description: "require or disallow Unicode byte order mark (BOM)",
+ category: "Stylistic Issues",
+ recommended: false,
+ url: "https://eslint.org/docs/rules/unicode-bom"
+ },
+
+ fixable: "whitespace",
+
+ schema: [
+ {
+ enum: ["always", "never"]
+ }
+ ],
+ messages: {
+ expected: "Expected Unicode BOM (Byte Order Mark).",
+ unexpected: "Unexpected Unicode BOM (Byte Order Mark)."
+ }
+ },
+
+ create(context) {
+
+ //--------------------------------------------------------------------------
+ // Public
+ //--------------------------------------------------------------------------
+
+ return {
+
+ Program: function checkUnicodeBOM(node) {
+
+ const sourceCode = context.getSourceCode(),
+ location = { column: 0, line: 1 },
+ requireBOM = context.options[0] || "never";
+
+ if (!sourceCode.hasBOM && (requireBOM === "always")) {
+ context.report({
+ node,
+ loc: location,
+ messageId: "expected",
+ fix(fixer) {
+ return fixer.insertTextBeforeRange([0, 1], "\uFEFF");
+ }
+ });
+ } else if (sourceCode.hasBOM && (requireBOM === "never")) {
+ context.report({
+ node,
+ loc: location,
+ messageId: "unexpected",
+ fix(fixer) {
+ return fixer.removeRange([-1, 0]);
+ }
+ });
+ }
+ }
+
+ };
+
+ }
+};