buffer: misc logic simplification

Includes:
* No need for `typeof` when checking undefined.
* length is coerced to uint so no need to check if < 0.
* Stay consistent and always throw `new` errors.
* Returning offset + magic number in every write is error prone. Instead
  return the central write function which returns the correct offset.

lib/buffer.js

@@ -147,7 +147,7 @@ Buffer.concat = function(list, length) {
   if (!Array.isArray(list))
     throw new TypeError('Usage: Buffer.concat(list[, length])');
 
-  if (typeof length === 'undefined') {
+  if (length === undefined) {
     length = 0;
     for (var i = 0; i < list.length; i++)
       length += list[i].length;
@@ -162,9 +162,6 @@ Buffer.concat = function(list, length) {
   else if (list.length === 1)
     return list[0];
 
-  if (length < 0)
-    throw new RangeError('length is not a positive number');
-
   var buffer = new Buffer(length);
   var pos = 0;
   for (var i = 0; i < list.length; i++) {
@@ -187,7 +184,7 @@ Buffer.prototype.toString = function(encoding, start, end) {
   encoding = !!encoding ? (encoding + '').toLowerCase() : 'utf8';
 
   start = ~~start;
-  end = typeof end === 'undefined' ? this.length : ~~end;
+  end = (end === undefined) ? this.length : ~~end;
 
   if (start < 0) start = 0;
   if (end > this.length) end = this.length;
@@ -256,10 +253,9 @@ var writeMsg = '.write(string, encoding, offset, length) is deprecated.' +
                ' Use write(string, offset, length, encoding) instead.';
 Buffer.prototype.write = function(string, offset, length, encoding) {
   // allow write(string, encoding)
-  if (typeof offset === 'string' && typeof length === 'undefined') {
+  if (typeof offset === 'string' && length === undefined) {
     encoding = offset;
     offset = 0;
-    length = undefined;
 
   // allow write(string, offset[, length], encoding)
   } else if (isFinite(offset)) {
@@ -290,7 +286,7 @@ Buffer.prototype.write = function(string, offset, length, encoding) {
   }
 
   var remaining = this.length - offset;
-  if (typeof length === 'undefined' || length > remaining)
+  if (length === undefined || length > remaining)
     length = remaining;
 
   encoding = !!encoding ? (encoding + '').toLowerCase() : 'utf8';
@@ -350,7 +346,7 @@ Buffer.prototype.toJSON = function() {
 Buffer.prototype.slice = function(start, end) {
   var len = this.length;
   start = ~~start;
-  end = typeof end === 'undefined' ? len : ~~end;
+  end = (end === undefined) ? len : ~~end;
 
   if (start < 0) {
     start += len;
@@ -563,9 +559,9 @@ Buffer.prototype.readInt32BE = function(offset, noAssert) {
 
 function checkInt(buffer, value, offset, ext, max, min) {
   if (value > max || value < min)
-    throw TypeError('value is out of bounds');
+    throw new TypeError('value is out of bounds');
   if (offset < 0 || offset + ext > buffer.length || buffer.length + offset < 0)
-    throw RangeError('index out of range');
+    throw new RangeError('index out of range');
 }
 
 
@@ -587,6 +583,7 @@ function writeUInt16(buffer, value, offset, isBigEndian) {
     buffer[offset + 1] = (value & 0xff00) >>> 8;
     buffer[offset] = value & 0x00ff;
   }
+  return offset + 2;
 }
 
 
@@ -595,8 +592,7 @@ Buffer.prototype.writeUInt16LE = function(value, offset, noAssert) {
   offset = ~~offset;
   if (!noAssert)
     checkInt(this, value, offset, 2, 0xffff, 0);
-  writeUInt16(this, value, offset, false);
+  return writeUInt16(this, value, offset, false);
-  return offset + 2;
 };
 
 
@@ -605,8 +601,7 @@ Buffer.prototype.writeUInt16BE = function(value, offset, noAssert) {
   offset = ~~offset;
   if (!noAssert)
     checkInt(this, value, offset, 2, 0xffff, 0);
-  writeUInt16(this, value, offset, true);
+  return writeUInt16(this, value, offset, true);
-  return offset + 2;
 };
 
 
@@ -622,6 +617,7 @@ function writeUInt32(buffer, value, offset, isBigEndian) {
     buffer[offset + 1] = (value >>> 8) & 0xff;
     buffer[offset] = value & 0xff;
   }
+  return offset + 4;
 }
 
 
@@ -630,8 +626,7 @@ Buffer.prototype.writeUInt32LE = function(value, offset, noAssert) {
   offset = ~~offset;
   if (!noAssert)
     checkInt(this, value, offset, 4, 0xffffffff, 0);
-  writeUInt32(this, value, offset, false);
+  return writeUInt32(this, value, offset, false);
-  return offset + 4;
 };
 
 
@@ -640,8 +635,7 @@ Buffer.prototype.writeUInt32BE = function(value, offset, noAssert) {
   offset = ~~offset;
   if (!noAssert)
     checkInt(this, value, offset, 4, 0xffffffff, 0);
-  writeUInt32(this, value, offset, true);
+  return writeUInt32(this, value, offset, true);
-  return offset + 4;
 };
 
 
@@ -699,8 +693,7 @@ Buffer.prototype.writeInt16LE = function(value, offset, noAssert) {
   if (!noAssert)
     checkInt(this, value, offset, 2, 0x7fff, -0x8000);
   if (value < 0) value = 0xffff + value + 1;
-  writeUInt16(this, value, offset, false);
+  return writeUInt16(this, value, offset, false);
-  return offset + 2;
 };
 
 
@@ -710,8 +703,7 @@ Buffer.prototype.writeInt16BE = function(value, offset, noAssert) {
   if (!noAssert)
     checkInt(this, value, offset, 2, 0x7fff, -0x8000);
   if (value < 0) value = 0xffff + value + 1;
-  writeUInt16(this, value, offset, true);
+  return writeUInt16(this, value, offset, true);
-  return offset + 2;
 };
 
 
@@ -721,8 +713,7 @@ Buffer.prototype.writeInt32LE = function(value, offset, noAssert) {
   if (!noAssert)
     checkInt(this, value, offset, 4, 0x7fffffff, -0x80000000);
   if (value < 0) value = 0xffffffff + value + 1;
-  writeUInt32(this, value, offset, false);
+  return writeUInt32(this, value, offset, false);
-  return offset + 4;
 };
 
 
@@ -732,6 +723,5 @@ Buffer.prototype.writeInt32BE = function(value, offset, noAssert) {
   if (!noAssert)
     checkInt(this, value, offset, 4, 0x7fffffff, -0x80000000);
   if (value < 0) value = 0xffffffff + value + 1;
-  writeUInt32(this, value, offset, true);
+  return writeUInt32(this, value, offset, true);
-  return offset + 4;
 };