chain-able
Version:
interfaces that describe their intentions.
39 lines (38 loc) • 716 B
JavaScript
/**
* @desc Checks if `value` is `undefined`.
* @category Lang
*
* @param {*} x value
* @return {boolean} isUndefined
*
* @since 4.0.0-alpha.1
* @memberOf is
* @func isUndefined
*
* @see is/nullOrUndefined
* @see https://github.com/infernojs/inferno/blob/master/packages/inferno-shared/src/index.ts#L57
*
* @NOTE || typeof x === 'undefined'
*
* @example
*
* isUndefined(undefined)
* //=> true
* isUndefined(void 0)
* //=> true
*
* isUndefined(null)
* //=> false
* isUndefined(NaN)
* //=> false
* isUndefined({})
* //=> false
* isUndefined('')
* //=> false
* isUndefined(1)
* //=> false
* isUndefined(false)
* //=> false
*
*/
module.exports = x => x === undefined