update deps, es6ify code

.travis.yml

@@ -4,10 +4,9 @@ os:
   - linux
 
 node_js:
-  - "4"
-  - "6"
-  - "7"
   - "8"
+  - "10"
+  - "11"
 
 sudo: required
 

js/node-gd.js

@@ -1,32 +1,33 @@
-var util = require('util');
-var fs = require('fs');
+const fs = require('fs');
+const path = require('path');
 
-var bindings;
-var versionMessage = 'Node-gd: method __METHOD__ only available from libgd2 version 2.1.1. '
+let bindings;
+
+let versionMessage = 'Node-gd: method __METHOD__ only available from libgd2 version 2.1.1. '
     + 'Current installed is ';
 
 function openFormatFn(fmt) {
   return function() {
-    var args = [];
-    for (var i = 0; i < arguments.length; i++) {
+    const args = [];
+    for (let i = 0; i < arguments.length; i++) {
       args[i] = (arguments[i]);
     }
 
-    var file = args.shift();
-    var cb = args.pop();
+    const file = args.shift();
+    const cb = args.pop();
 
     if (typeof cb !== "function") {
-      return bindings["createFrom" + fmt].apply(this, arguments);
+      return bindings[`createFrom${fmt}`].apply(this, arguments);
     }
 
     return fs.readFile(file, function (err, data) {
-      var img;
+      let img;
       if (err) {
         return cb(err);
       } else {
         try {
-          img = bindings["createFrom" + fmt + "Ptr"](data);
-        } catch(e) {
+          img = bindings[`createFrom${fmt}Ptr`](data);
+        } catch (e) {
           return cb(e);
         }
         return cb(null, img);
@@ -39,28 +40,28 @@ function saveFormatFn(format) {
   format = format.toLowerCase();
 
   return function () {
-    var data;
-    var args = [];
-    for (var i = 0; i < arguments.length; i++) {
+    const args = [];
+    for (let i = 0; i < arguments.length; i++) {
       args[i] = (arguments[i]);
     }
 
-    var filename = args.shift();
-    var callback = args.pop();
+    const filename = args.shift();
+    const callback = args.pop();
 
     if (typeof callback !== "function") {
       return this[format].apply(this, arguments);
     }
 
-    data = this[format + "Ptr"].apply(this, args);
+    const data = this[`${format}Ptr`].apply(this, args);
     return fs.writeFile(filename, data, "binary", callback);
   };
 }
 
 function exportFormats() {
-  var format, formats, valid, version = bindings.getGDVersion();
+  let valid;
+  const version = bindings.getGDVersion();
 
-  formats = {
+  const formats = {
     Jpeg: [1, 1],
     Png: [1, 1],
     Gif: [1, 1],
@@ -82,20 +83,20 @@ function exportFormats() {
     formats.Webp = [1, 1];
   }
 
-  for (format in formats) {
+  for (const format in formats) {
     valid = formats[format];
     if (!!valid[0]) {
-      bindings["open" + format] = openFormatFn(format);
+      bindings[`open${format}`] = openFormatFn(format);
     }
     if (!!valid[1]) {
-      bindings.Image.prototype["save" + format] = saveFormatFn(format);
+      bindings.Image.prototype[`save${format}`] = saveFormatFn(format);
     }
   }
 }
 
-var libPaths = [
-  __dirname + '/../build/Release/node_gd.node',
-  __dirname + '/../build/default/node_gd.node'
+const libPaths = [
+  path.normalize(`${__dirname}/../build/Release/node_gd.node`),
+  path.normalize(`${__dirname}/../build/default/node_gd.node`)
 ];
 
 try {
@@ -130,32 +131,32 @@ if (bindings.getGDVersion() >= '2.1.1') {
   };
 
   bindings.openFile = function() {
-    var args = [];
-    var image;
-    for (var i = 0; i < arguments.length; i++) {
+    const args = [];
+    let image;
+    for (let i = 0; i < arguments.length; i++) {
       args[i] = (arguments[i]);
     }
 
-    var callback = args[args.length - 1];
+    const callback = args[args.length - 1];
     if (typeof callback !== "function") {
       return this.createFromFile.apply(this, args);
     }
 
     try {
       image = this.createFromFile.apply(this, args);
-    } catch(e) {
+    } catch (e) {
       return callback(e);
     }
     return callback(null, image);
   };
 } else {
   bindings.Image.prototype.saveFile = function() {
     throw new Error(versionMessage.replace('__METHOD__', 'gd.Image#saveFile()'));
-  }
+  };
 
   bindings.openFile = function() {
     throw new Error(versionMessage.replace('__METHOD__', 'gd.openFile()'));
-  }
+  };
 }
 
 module.exports = bindings;