identify file type by file magic numbers.
npm install whether+ Magic numbers are the first bits of a file which uniquely identify the type of file.
+ see details.
``
npm install whether
check an image is exactly the given type.
`javascript
var whether = require('whether').create();
whether('path/to/image').is('jpg'); // will return boolean
// or async way
whether('path/to/image').is('jpg', callback);
// check whether the file content type is matched with the file extension.
whether('path/to/image.jpg').isMatched(); //matched with jpg type, return boolean.
// or aync way
whether('path/to/image.jpg').isMatched(callback);
// isValid is an alias
whether('path/to/image.jpg').isValid(callback);
`
identify a file with magic numbers. keep in mind the identify is a class method.
`javascript
var Whether = require('whether');
// identify jpg file, will return boolean
Whether.identify('path/to/image', 'FFD8FF');
// async way
Whether.identify('path/to/image', 'FFD8FF', callback);
`
see the config.js
you can define your map.
`javascript
// will only overwrite the exist keys
var whether = require('whether')({
exts: {
'ext1': '...',
'ext2': '...',
'ext3': '...'
}
});
// then use these definitions.
whether('path/to/image').is('ext1');
whether('path/to/image.ext2').isMatched();
`
sometimes, we want to check a file is some kind of file.
eg: whether a file is an image.
define a check method, use an array to tell which exts are included.
`javascript
// define in config.
var whether = require('whether')({
defs: {
isImage: ['png', 'gif', 'jpg', 'bmp'],
isMS: ['doc', 'ppt', 'xls'],
...
},
exts: {...}
});
// use the defined methods
whether('path/to/image').isImage();
// async way
whether('path/to/image').isImage(callback);
// define instantly
var whether = require('whether')({
exts: {
ext1: '...',
ext2: '...'
}
});
whether.define('isSomething', ['ext1', 'ext2']);
// then use
whether('path/to/file').isSomething();
whether('path/to/file').isSomething(callback);
``
notice: all the exts used in methods definitions should have defined in the config.exts