isNumber.js

var isObjectLike = require('../internal/isObjectLike');

/** `Object#toString` result references. */
var numberTag = '[object Number]';

/** Used for native method references. */
var objectProto = Object.prototype;

/**
 * Used to resolve the [`toStringTag`](https://people.mozilla.org/~jorendorff/es6-draft.html#sec-object.prototype.tostring)
 * of values.
 */
var objToString = objectProto.toString;

/**
 * Checks if `value` is classified as a `Number` primitive or object.
 *
 * **Note:** To exclude `Infinity`, `-Infinity`, and `NaN`, which are classified
 * as numbers, use the `_.isFinite` method.
 *
 * @static
 * @memberOf _
 * @category Lang
 * @param {*} value The value to check.
 * @returns {boolean} Returns `true` if `value` is correctly classified, else `false`.
 * @example
 *
 * _.isNumber(8.4);
 * // => true
 *
 * _.isNumber(NaN);
 * // => true
 *
 * _.isNumber('8.4');
 * // => false
 */
function isNumber(value) {
  return typeof value == 'number' || (isObjectLike(value) && objToString.call(value) == numberTag);
}

module.exports = isNumber;