exifreader - npm Package Compare versions

Comparing version 4.8.1 to 4.9.0

package.json

 {
   "name": "exifreader",
-  "version": "4.8.1",
+  "version": "4.9.0",
   "description": "Library that parses Exif metadata in images.",
@@ -5,0 +5,0 @@ "author": "Mattias Wallander <[e-mail]>",

README.md

@@ -206,2 +206,24 @@ ExifReader
 
+#### Read only part of file
+
+If you only want to read part of the image file you can use the `length` option:
+
+```javascript
+const tags = await ExifReader.load(filename, {length: 128 * 1024});
+```
+
+This will load only the first 128 KiB of the file. This could be useful if you
+know the metadata is located at the beginning of the file. Just be aware that
+it's common for the metadata to be spread out over a larger area so please try
+it out on your set of files to know if it's suitable for your situation.
+
+Note that this option only works when ExifReader handles the loading of the
+file. If e.g. a JavaScript File object from a form file field is passed into
+ExifReader the whole file will already have been loaded into memory and it's too
+late. More specifically the length option will work for 1. local files when
+running through Node.js, and 2. remote files when passing a URL. For the latter,
+if doing this through a web browser, make sure the remote server is either on
+the same origin (domain) as your script or that the server is passing correct
+CORS headers, specifically allowing the `Range` header.
+
 #### Unknown tags
@@ -429,3 +451,4 @@
     possibly Exif too if they come in an irregular order) so please check if
-    this optimization fits your use case.
+    this optimization fits your use case. Use the `length` option to only read
+    the beginning of the file. See above for more details on that.
 
@@ -432,0 +455,0 @@ Testing

src/exif-reader.js

@@ -37,3 +37,3 @@ /**
     if (isFilePathOrURL(data)) {
-        return loadFile(data).then((fileContents) => loadFromData(fileContents, options));
+        return loadFile(data, options).then((fileContents) => loadFromData(fileContents, options));
     }
@@ -50,22 +50,35 @@ if (isBrowserFileObject(data)) {
 
-function loadFile(filename) {
+function loadFile(filename, options) {
     if (/^https?:\/\//.test(filename)) {
         if (typeof fetch !== 'undefined') {
-            return browserFetchRemoteFile(filename);
+            return browserFetchRemoteFile(filename, options);
         }
 
-        return nodeFetchRemoteFile(filename);
+        return nodeFetchRemoteFile(filename, options);
     }
 
-    return loadLocalFile(filename);
+    return loadLocalFile(filename, options);
 }
 
-function browserFetchRemoteFile(url) {
-    return fetch(url).then((response) => response.arrayBuffer());
+function browserFetchRemoteFile(url, {length} = {}) {
+    const options = {method: 'GET'};
+    if (Number.isInteger(length) && length >= 0) {
+        options.headers = {
+            range: `bytes=0-${length - 1}`,
+        };
+    }
+    return fetch(url, options).then((response) => response.arrayBuffer());
 }
 
-function nodeFetchRemoteFile(url) {
+function nodeFetchRemoteFile(url, {length} = {}) {
     return new Promise((resolve, reject) => {
+        const options = {};
+        if (Number.isInteger(length) && length >= 0) {
+            options.headers = {
+                range: `bytes=0-${length - 1}`,
+            };
+        }
+
         const get = requireNodeGet(url);
-        get(url, (response) => {
+        get(url, options, (response) => {
             if ((response.statusCode >= 200) && (response.statusCode <= 299)) {
@@ -91,3 +104,3 @@ const data = [];
 
-function loadLocalFile(filename) {
+function loadLocalFile(filename, {length} = {}) {
     return new Promise((resolve, reject) => {
@@ -103,4 +116,9 @@ const fs = requireNodeFs();
                     } else {
-                        const buffer = Buffer.alloc(stat.size);
-                        fs.read(fd, {buffer}, (error) => {
+                        const size = Math.min(stat.size, length !== undefined ? length : stat.size);
+                        const buffer = Buffer.alloc(size);
+                        const options = {
+                            buffer,
+                            length: size
+                        };
+                        fs.read(fd, options, (error) => {
                             if (error) {
@@ -107,0 +125,0 @@ reject(error);

No alert changes

Improved metrics

Total package byte prevSize

544892

0.7%

Lines of code

5624

0.34%

Number of lines in readme file

573

4.18%

No dependency changes