Implement byteLength method.

README.md

@@ -27,6 +27,9 @@ buf = iconv.encode("Sample input string", 'win1251');
 
 // Check if encoding is supported
 iconv.encodingExists("us-ascii")
+
+// Calculate actual length in bytes.
+len = iconv.byteLength('hello, world!', 'win1251')
 ```
 
 ### Streaming API (Node v0.10+)

encodings/dbcs-codec.js

@@ -431,6 +431,13 @@ DBCSEncoder.prototype.end = function() {
     return newBuf.slice(0, j);
 }
 
+DBCSEncoder.prototype.byteLength = function(str) {
+    var res = this.write(str);
+    var trail = this.end();
+
+    return res.length + ((trail === undefined) ? 0 : trail.length);
+}
+
 // Export for testing
 DBCSEncoder.prototype.findIdx = findIdx;
 

encodings/internal.js

@@ -75,6 +75,10 @@ InternalEncoder.prototype.write = function(str) {
 InternalEncoder.prototype.end = function() {
 }
 
+InternalEncoder.prototype.byteLength = function(str) {
+    return Buffer.byteLength(str, this.enc)
+}
+
 
 //------------------------------------------------------------------------------
 // Except base64 encoder, which must keep its state.
@@ -96,6 +100,10 @@ InternalEncoderBase64.prototype.end = function() {
     return new Buffer(this.prevStr, "base64");
 }
 
+InternalEncoderBase64.prototype.byteLength = function(str) {
+    return Buffer.byteLength(str, "base64");
+}
+
 
 //------------------------------------------------------------------------------
 // CESU-8 encoder is also special.
@@ -127,6 +135,10 @@ InternalEncoderCesu8.prototype.write = function(str) {
 InternalEncoderCesu8.prototype.end = function() {
 }
 
+InternalEncoderCesu8.prototype.byteLength = function(str) {
+    return this.write(str).length;
+}
+
 //------------------------------------------------------------------------------
 // CESU-8 decoder is not implemented in Node v4.0+
 

encodings/sbcs-codec.js

@@ -48,6 +48,10 @@ SBCSEncoder.prototype.write = function(str) {
     return buf;
 }
 
+SBCSEncoder.prototype.byteLength = function(str) {
+    return str.length;
+}
+
 SBCSEncoder.prototype.end = function() {
 }
 

encodings/utf16.js

@@ -30,6 +30,10 @@ Utf16BEEncoder.prototype.write = function(str) {
 Utf16BEEncoder.prototype.end = function() {
 }
 
+Utf16BEEncoder.prototype.byteLength = function(str) {
+    return Buffer.byteLength(str, 'ucs2');
+}
+
 
 // -- Decoding
 
@@ -98,6 +102,10 @@ Utf16Encoder.prototype.end = function() {
     return this.encoder.end();
 }
 
+Utf16Encoder.prototype.byteLength = function(str) {
+    return Buffer.byteLength(str, 'ucs2');
+}
+
 
 // -- Decoding
 

encodings/utf7.js

@@ -36,6 +36,10 @@ Utf7Encoder.prototype.write = function(str) {
 Utf7Encoder.prototype.end = function() {
 }
 
+Utf7Encoder.prototype.byteLength = function(str) {
+    return this.write(str).length;
+}
+
 
 // -- Decoding
 

lib/index.d.ts

@@ -12,6 +12,8 @@ declare module 'iconv-lite' {
 
 	export function encodingExists(encoding: string): boolean;
 
+	export function byteLength(content: string, encoding: string): Number;
+
 	export function decodeStream(encoding: string, options?: Options): NodeJS.ReadWriteStream;
 
 	export function encodeStream(encoding: string, options?: Options): NodeJS.ReadWriteStream;

lib/index.js

@@ -128,6 +128,11 @@ iconv.getDecoder = function getDecoder(encoding, options) {
     return decoder;
 }
 
+iconv.byteLength = function byteLength(str, encoding) {
+    str = "" + (str || ""); // Ensure string.
+
+    return iconv.getEncoder(encoding).byteLength(str)
+}
 
 // Load extensions in Node. All of them are omitted in Browserify build via 'browser' field in package.json.
 var nodeVer = typeof process !== 'undefined' && process.versions && process.versions.node;

test/cesu8-test.js

@@ -20,4 +20,7 @@ describe("CESU-8 codec", function() {
         assert.equal(iconv.decode(new Buffer("eda081edb080", 'hex'), "cesu8"), "𐐀");
         assert.equal(iconv.decode(new Buffer("eda0bdedb8b1", 'hex'), "cesu8"), "😱");
     });
+    it('has correct length in bytes', function() {
+        assert.equal(iconv.byteLength("😱", "cesu8"), Buffer.byteLength('eda0bdedb8b1', 'hex'));
+    });
 });

test/dbcs-test.js

@@ -243,5 +243,17 @@ describe("Full DBCS encoding tests", function() {
             });
         })(enc);
     }
-});
+
+    it('correct length in bytes', function() {
+        var testStringLatin1 = 'hello';
+
+        for (var enc in iconv.encodings) {
+            if (iconv.encodings[enc].type === '_dbcs') {
+                assert.equal(iconv.byteLength(testStringLatin1, enc), testStringLatin1.length);
+                return;
+            }
+        }
 
+        this.skip();
+    });
+});

test/main-test.js

@@ -78,4 +78,12 @@ describe("Generic UTF8-UCS2 tests", function() {
         delete Object.prototype.permits;
         delete Array.prototype.sample2;
     });
+
+    it('Internal encodings has correct length in bytes', function() {
+        assert.equal(iconv.byteLength(testStringLatin1, 'utf8'), Buffer.byteLength(testStringLatin1, 'utf8'));
+        assert.equal(iconv.byteLength(testStringLatin1, 'ucs2'), Buffer.byteLength(testStringLatin1, 'ucs2'));
+        assert.equal(iconv.byteLength(testStringLatin1, 'binary'), Buffer.byteLength(testStringLatin1, 'binary'));
+        assert.equal(iconv.byteLength(testStringBase64, 'base64'), Buffer.byteLength(testStringBase64, 'base64'));
+        assert.equal(iconv.byteLength(testStringHex, 'hex'), Buffer.byteLength(testStringHex, 'hex'));
+    });
 });

test/sbcs-test.js

@@ -157,5 +157,17 @@ describe("Full SBCS encoding tests", function() {
             assert.strictEqual(iconv.encode(str, enc).toString('hex'), convBack.convert(new Buffer(str)).toString('hex'));
             */
         })(enc);
-});
 
+    it('correct length in bytes', function() {
+        var testStringLatin1 = 'hello';
+
+        for (var enc in iconv.encodings) {
+            if (iconv.encodings[enc].type === '_sbcs') {
+                assert.equal(iconv.byteLength(testStringLatin1, enc), testStringLatin1.length);
+                return;
+            }
+        }
+
+        this.skip();
+    });
+});

test/utf16-test.js

@@ -20,6 +20,10 @@ describe("UTF-16BE codec", function() {
     it("decodes uneven length buffers with no error", function() {
         assert.equal(iconv.decode(new Buffer([0, 0x61, 0]), 'UTF16-BE'), "a");
     });
+
+    it('has correct length in bytes', function() {
+        assert.equal(iconv.byteLength(testStr, 'UTF16-BE'), utf16beBuf.length);
+    });
 });
 
 describe("UTF-16 encoder", function() {
@@ -31,6 +35,10 @@ describe("UTF-16 encoder", function() {
         assert.equal(iconv.encode(testStr, "utf-16", {use: 'UTF-16LE'}).toString('hex'), 
             utf16leBOM.toString('hex') + new Buffer(testStr, 'ucs2').toString('hex'));
     });
+
+    it('has correct length in bytes', function() {
+        assert.equal(iconv.byteLength(testStr, 'utf-16'), utf16leBuf.length);
+    });
 });
 
 describe("UTF-16 decoder", function() {

test/utf7-test.js

@@ -85,6 +85,10 @@ describe("UTF-7 codec", function() {
         assert.equal(iconv.decode(new Buffer("+AMAA4A!Next"), 'utf-7'), "\u00c0\u00e0!Next");
 
     });
+
+    it('has correct length in bytes', function() {
+        assert.equal(iconv.byteLength('A\u2262\u0391.', 'utf-7'), 'A+ImIDkQ-.'.length);
+    });
 });
 
 describe("UTF-7-IMAP codec", function() {