compile using babel for compatibility with older versions

.babelrc.json

@@ -0,0 +1,8 @@
+{
+  "presets": [
+    ["@babel/preset-env"]
+  ],
+  "plugins": [
+    ["transform-es2017-object-entries"]
+  ]
+}

.editorconfig

@@ -16,3 +16,6 @@ indent_size = 2
 
 [*.pegjs]
 indent_size = 2
+
+[*.yml]
+indent_size = 2

.travis.yml

@@ -4,10 +4,28 @@ script:
   - npm run build
   - npm run test:ci
 node_js:
+  - 6
   - 8
   - 10
   - 12
 
+before_install:
+  - npm config set depth 0
+before_script: >
+  node_version=$(node -v);
+  if [ ${node_version:3:1} = "." ]; then
+    echo "Node 10+"
+    npm install --no-save "eslint@6"
+    else
+      if [ ${node_version:1:1} -ge 8 ]; then
+        echo "Node 8+"
+        npm install --no-save "eslint@5"
+      else
+        echo "Node 6+"
+        npm install --no-save "eslint@5" mocha@6.2.2 nyc@14.1.1
+      fi
+  fi
+
 matrix:
   include:
     - name: Lint

package.json

@@ -33,7 +33,7 @@
     "build:parser": "rm parser.js && pegjs --cache --format umd -o \"parser.js\" \"grammar.pegjs\"",
     "build:browser": "rollup -c",
     "build": "npm run build:parser && npm run build:browser",
-    "mocha": "mocha --require chai/register-assert --require esm tests",
+    "mocha": "mocha --require chai/register-assert --require @babel/register tests",
     "test": "nyc npm run mocha && npm run lint",
     "test:ci": "npm run mocha",
     "lint": "eslint ."
@@ -51,22 +51,26 @@
     "query"
   ],
   "devDependencies": {
+    "@babel/core": "^7.9.0",
+    "@babel/preset-env": "^7.9.0",
+    "@babel/register": "^7.9.0",
     "@rollup/plugin-commonjs": "^11.0.2",
     "@rollup/plugin-json": "^4.0.2",
     "@rollup/plugin-node-resolve": "^7.1.1",
+    "babel-plugin-transform-es2017-object-entries": "0.0.5",
     "chai": "^4.2.0",
     "eslint": "^6.8.0",
-    "esm": "^3.2.25",
     "esprima": "~4.0.1",
     "mocha": "^7.1.1",
     "nyc": "^15.0.0",
     "pegjs": "~0.10.0",
     "rollup": "^1.32.0",
+    "rollup-plugin-babel": "^4.4.0",
     "rollup-plugin-terser": "^5.2.0"
   },
   "license": "BSD-3-Clause",
   "engines": {
-    "node": ">=8.0"
+    "node": ">=0.10"
   },
   "dependencies": {
     "estraverse": "^5.0.0"

rollup.config.js

@@ -4,6 +4,8 @@ import nodeResolve from '@rollup/plugin-node-resolve';
 import commonjs from '@rollup/plugin-commonjs';
 import json from '@rollup/plugin-json';
 
+import babel from 'rollup-plugin-babel';
+
 /**
  * @external RollupConfig
  * @type {PlainObject}
@@ -30,7 +32,8 @@ function getRollupObject ({ minifying, format = 'umd' } = {}) {
         plugins: [
             json(),
             nodeResolve(),
-            commonjs()
+            commonjs(),
+            babel()
         ]
     };
     if (minifying) {

tests/queryAttribute.js

@@ -177,12 +177,14 @@ describe('Attribute query', function () {
         ]);
     });
 
-    it('regexp flag (s)', function () {
-        const matches = esquery(literal, '[value=/\f.\r/s]');
-        assert.includeMembers(matches, [
-            literal.body[0].declarations[0].init
-        ]);
-    });
+    if ((/^(?:[89]|\d{2,})\./).test(process.version)) {
+        it('regexp flag (s)', function () {
+            const matches = esquery(literal, '[value=/\f.\r/s]');
+            assert.includeMembers(matches, [
+                literal.body[0].declarations[0].init
+            ]);
+        });
+    }
 
     it('regexp flag (m)', function () {
         const matches = esquery(literal, '[value=/^\r/m]');