diff --git a/lib/data.js b/lib/data.js
index 7ca22e4..e3ae798 100644
--- a/lib/data.js
+++ b/lib/data.js
@@ -1,8 +1,5 @@
 class Data {
-  constructor(data) {
-    if (data == null) {
-      data = [];
-    }
+  constructor(data = []) {
     this.data = data;
     this.pos = 0;
     this.length = this.data.length;
@@ -88,11 +85,7 @@ class Data {
 
   readString(length) {
     const ret = [];
-    for (
-      let i = 0, end = length, asc = 0 <= end;
-      asc ? i < end : i > end;
-      asc ? i++ : i--
-    ) {
+    for (let i = 0; i < length; i++) {
       ret[i] = String.fromCharCode(this.readByte());
     }
 
@@ -186,11 +179,7 @@ class Data {
 
   read(bytes) {
     const buf = [];
-    for (
-      let i = 0, end = bytes, asc = 0 <= end;
-      asc ? i < end : i > end;
-      asc ? i++ : i--
-    ) {
+    for (let i = 0; i < bytes; i++) {
       buf.push(this.readByte());
     }
 
diff --git a/lib/font/afm.js b/lib/font/afm.js
index cafeb02..d54aaab 100644
--- a/lib/font/afm.js
+++ b/lib/font/afm.js
@@ -181,11 +181,7 @@ class AFMFont {
 
   encodeText(text) {
     const res = [];
-    for (
-      let i = 0, end = text.length, asc = 0 <= end;
-      asc ? i < end : i > end;
-      asc ? i++ : i--
-    ) {
+    for (let i = 0, len = text.length; i < len; i++) {
       let char = text.charCodeAt(i);
       char = WIN_ANSI_MAP[char] || char;
       res.push(char.toString(16));
@@ -197,11 +193,7 @@ class AFMFont {
   glyphsForString(string) {
     const glyphs = [];
 
-    for (
-      let i = 0, end = string.length, asc = 0 <= end;
-      asc ? i < end : i > end;
-      asc ? i++ : i--
-    ) {
+    for (let i = 0, len = string.length; i < len; i++) {
       const charCode = string.charCodeAt(i);
       glyphs.push(this.characterToGlyph(charCode));
     }
diff --git a/lib/font/embedded.js b/lib/font/embedded.js
index a185d2d..64f4548 100644
--- a/lib/font/embedded.js
+++ b/lib/font/embedded.js
@@ -60,15 +60,12 @@ class EmbeddedFont extends PDFFont {
 
   layout(text, features, onlyWidth) {
     // Skip the cache if any user defined features are applied
-    if (onlyWidth == null) {
-      onlyWidth = false;
-    }
     if (features) {
       return this.layoutRun(text, features);
     }
 
-    const glyphs = onlyWidth ? null : [];
-    const positions = onlyWidth ? null : [];
+    let glyphs = onlyWidth ? null : [];
+    let positions = onlyWidth ? null : [];
     let advanceWidth = 0;
 
     // Split the string by words to increase cache efficiency.
@@ -83,8 +80,8 @@ class EmbeddedFont extends PDFFont {
       ) {
         const run = this.layoutCached(text.slice(last, ++index));
         if (!onlyWidth) {
-          glyphs.push(...(run.glyphs || []));
-          positions.push(...(run.positions || []));
+          glyphs = glyphs.concat(run.glyphs);
+          positions = positions.concat(run.positions);
         }
 
         advanceWidth += run.advanceWidth;
diff --git a/lib/gradient.js b/lib/gradient.js
index c0e458d..f499f36 100644
--- a/lib/gradient.js
+++ b/lib/gradient.js
@@ -45,8 +45,7 @@ class PDFGradient {
   }
 
   embed(m) {
-    let asc, i;
-    let end, fn;
+    let fn;
     if (this.stops.length === 0) {
       return;
     }
@@ -63,13 +62,9 @@ class PDFGradient {
     const encode = [];
     const stops = [];
 
-    for (
-      i = 0, end = this.stops.length - 1, asc = 0 <= end;
-      asc ? i < end : i > end;
-      asc ? i++ : i--
-    ) {
+    for (let i = 0, stopsLength = this.stops.length - 1; i < stopsLength; i++) {
       encode.push(0, 1);
-      if (i + 2 !== this.stops.length) {
+      if (i + 2 !== stopsLength) {
         bounds.push(this.stops[i + 1][0]);
       }
 
diff --git a/lib/mixins/text.js b/lib/mixins/text.js
index b1a1c58..1a00db2 100644
--- a/lib/mixins/text.js
+++ b/lib/mixins/text.js
@@ -81,16 +81,13 @@ export default {
   },
 
   heightOfString(text, options) {
-    if (options == null) {
-      options = {};
-    }
     const { x, y } = this;
 
     options = this._initOptions(options);
     options.height = Infinity; // don't break pages
 
     const lineGap = options.lineGap || this._lineGap || 0;
-    this._text(text, this.x, this.y, options, (line, options) => {
+    this._text(text, this.x, this.y, options, () => {
       return (this.y += this.currentLineHeight(true) + lineGap);
     });
 
@@ -205,22 +202,15 @@ export default {
     }
 
     // clone options object
-    options = (function() {
-      const opts = {};
-      for (let k in options) {
-        const v = options[k];
-        opts[k] = v;
-      }
-      return opts;
-    })();
+    const result = Object.assign({}, options);
 
     // extend options with previous values for continued text
     if (this._textOptions) {
       for (let key in this._textOptions) {
         const val = this._textOptions[key];
         if (key !== 'continued') {
-          if (options[key] == null) {
-            options[key] = val;
+          if (result[key] == null) {
+            result[key] = val;
           }
         }
       }
@@ -235,20 +225,20 @@ export default {
     }
 
     // wrap to margins if no x or y position passed
-    if (options.lineBreak !== false) {
-      if (options.width == null) {
-        options.width = this.page.width - this.x - this.page.margins.right;
+    if (result.lineBreak !== false) {
+      if (result.width == null) {
+        result.width = this.page.width - this.x - this.page.margins.right;
       }
     }
 
-    if (!options.columns) {
-      options.columns = 0;
+    if (!result.columns) {
+      result.columns = 0;
     }
-    if (options.columnGap == null) {
-      options.columnGap = 18;
+    if (result.columnGap == null) {
+      result.columnGap = 18;
     } // 1/4 inch
 
-    return options;
+    return result;
   },
 
   _line(text, options, wrapper) {
@@ -431,8 +421,8 @@ export default {
           word,
           options.features
         );
-        encoded.push(...(encodedWord || []));
-        positions.push(...(positionsWord || []));
+        encoded = encoded.concat(encodedWord);
+        positions = positions.concat(positionsWord);
 
         // add the word spacing to the end of the word
         // clone object because of cache
diff --git a/lib/mixins/vector.js b/lib/mixins/vector.js
index 4c6e853..1c657e5 100644
--- a/lib/mixins/vector.js
+++ b/lib/mixins/vector.js
@@ -195,11 +195,7 @@ export default {
     // calculate and render segments
     this.moveTo(ax, ay);
 
-    for (
-      let segIdx = 0, end = numSegs, asc = 0 <= end;
-      asc ? segIdx < end : segIdx > end;
-      asc ? segIdx++ : segIdx--
-    ) {
+    for (let segIdx = 0; segIdx < numSegs; segIdx++) {
       // starting control point
       const cp1x = ax + deltaCx;
       const cp1y = ay + deltaCy;
diff --git a/lib/outline.js b/lib/outline.js
index 2d6e423..c0d0c8b 100644
--- a/lib/outline.js
+++ b/lib/outline.js
@@ -40,9 +40,7 @@ class PDFOutline {
   }
 
   endOutline() {
-    let end;
     if (this.children.length > 0) {
-      let asc, i;
       if (this.options.expanded) {
         this.outlineData.Count = this.children.length;
       }
@@ -52,11 +50,7 @@ class PDFOutline {
       this.outlineData.First = first.dictionary;
       this.outlineData.Last = last.dictionary;
 
-      for (
-        i = 0, end = this.children.length, asc = 0 <= end;
-        asc ? i < end : i > end;
-        asc ? i++ : i--
-      ) {
+      for (let i = 0, len = this.children.length; i < len; i++) {
         const child = this.children[i];
         if (i > 0) {
           child.outlineData.Prev = this.children[i - 1].dictionary;
diff --git a/lib/path.js b/lib/path.js
index c9e6932..ddde05e 100644
--- a/lib/path.js
+++ b/lib/path.js
@@ -370,11 +370,7 @@ const arcToSegments = function(x, y, rx, ry, large, sweep, rotateX, ox, oy) {
   const segments = Math.ceil(Math.abs(th_arc / (Math.PI * 0.5 + 0.001)));
   const result = [];
 
-  for (
-    let i = 0, end = segments, asc = 0 <= end;
-    asc ? i < end : i > end;
-    asc ? i++ : i--
-  ) {
+  for (let i = 0; i < segments; i++) {
     const th2 = th0 + (i * th_arc) / segments;
     const th3 = th0 + ((i + 1) * th_arc) / segments;
     result[i] = [xc, yc, th2, th3, rx, ry, sin_th, cos_th];