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Underscore-to-camelCase converter (and vice versa) for strings and object keys in JavaScript.

When converting object keys, it will walk the structure, converting any nested objects (or arrays of nested objects) along the way. Handy for converting JSON between JavaScript and Ruby/Rails APIs.

Takes inspiration from Ember Data and copies some utility functions from Underscore.js.


Converting strings

humps.camelize('hello_world') // 'helloWorld'
humps.decamelize('fooBar') // 'foo_bar'
humps.decamelize('fooBarBaz', { separator: '-' }) // 'foo-bar-baz'

Converting object keys

var object = { attr_one: 'foo', attr_two: 'bar' }
humps.camelizeKeys(object); // { attrOne: 'foo', attrTwo: 'bar' }

Arrays of objects are also converted

var array = [{ attr_one: 'foo' }, { attr_one: 'bar' }]
humps.camelizeKeys(array); // [{ attrOne: 'foo' }, { attrOne: 'bar' }]

It also accepts a callback which can modify the conversion behavior. For example to prevent conversion of keys containing only uppercase letters or numbers:

humps.camelizeKeys(obj, function (key, convert) {
  return /^[A-Z0-9_]+$/.test(key) ? key : convert(key);
humps.decamelizeKeys(obj, function (key, convert, options) {
  return /^[A-Z0-9_]+$/.test(key) ? key : convert(key, options);

In order to use the callback with options use the process option:

humps.decamelizeKeys(obj, {
    separator: '-',
    process: function (key, convert, options) {
      return /^[A-Z0-9_]+$/.test(key) ? key : convert(key, options);



Removes any hypens, underscores, and whitespace characters, and uppercases the first character that follows.

humps.camelize('hello_world-foo bar') // 'helloWorldFooBar' 


Similar to humps.camelize(string), but also ensures that the first character is uppercase.

humps.pascalize('hello_world-foo bar') // 'HelloWorldFooBar' 

humps.decamelize(string, options)

Converts camelCased string to an underscore-separated string.

humps.decamelize('helloWorldFooBar') // 'hello_world_foo_bar' 

The separator can be customized with the separator option.

humps.decamelize('helloWorldFooBar', { separator: '-' }) // 'hello-world-foo-bar' 

By default, decamelize will only split words on capital letters (not numbers as in humps pre v1.0). To customize this behaviour, use the split option. This should be a regular expression which, when passed into String.prototype.split, produces an array of words (by default the regular expression is: /(?=[A-Z])/). For example, to treat numbers as uppercase:

humps.decamelize('helloWorld1', { split: /(?=[A-Z0-9])/ }) // 'hello_world_1' 

humps.depascalize(string, options)

Same as humps.decamelize above.

humps.camelizeKeys(object, options)

Converts object keys to camelCase. It also converts arrays of objects.

humps.pascalizeKeys(object, options)

Converts object keys to PascalCase. It also converts arrays of objects.

humps.decamelizeKeys(object, options)

Separates camelCased object keys with an underscore. It also converts arrays of objects. See humps.decamelize for details of options.

humps.depascalizeKeys(object, options)

See humps.decamelizeKeys.


humps is copyright © 2012+ Dom Christie and released under the MIT license.