lodash/lodash.initial/index.js

/**
 * lodash 4.0.2 (Custom Build) <https://lodash.com/>
 * Build: `lodash modularize exports="npm" -o ./`
 * Copyright 2012-2016 The Dojo Foundation <http://dojofoundation.org/>
 * Based on Underscore.js 1.8.3 <http://underscorejs.org/LICENSE>
 * Copyright 2009-2016 Jeremy Ashkenas, DocumentCloud and Investigative Reporters & Editors
 * Available under MIT license <https://lodash.com/license>
 */
var baseSlice = require('lodash._baseslice');

/** Used as references for various `Number` constants. */
var INFINITY = 1 / 0,
    MAX_INTEGER = 1.7976931348623157e+308,
    NAN = 0 / 0;

/** `Object#toString` result references. */
var funcTag = '[object Function]',
    genTag = '[object GeneratorFunction]';

/** Used to match leading and trailing whitespace. */
var reTrim = /^\s+|\s+$/g;

/** Used to detect bad signed hexadecimal string values. */
var reIsBadHex = /^[-+]0x[0-9a-f]+$/i;

/** Used to detect binary string values. */
var reIsBinary = /^0b[01]+$/i;

/** Used to detect octal string values. */
var reIsOctal = /^0o[0-7]+$/i;

/** Built-in method references without a dependency on `root`. */
var freeParseInt = parseInt;

/** Used for built-in method references. */
var objectProto = Object.prototype;

/**
 * Used to resolve the [`toStringTag`](http://ecma-international.org/ecma-262/6.0/#sec-object.prototype.tostring)
 * of values.
 */
var objectToString = objectProto.toString;

/**
 * Creates a slice of `array` with `n` elements dropped from the end.
 *
 * @static
 * @memberOf _
 * @category Array
 * @param {Array} array The array to query.
 * @param {number} [n=1] The number of elements to drop.
 * @param- {Object} [guard] Enables use as an iteratee for functions like `_.map`.
 * @returns {Array} Returns the slice of `array`.
 * @example
 *
 * _.dropRight([1, 2, 3]);
 * // => [1, 2]
 *
 * _.dropRight([1, 2, 3], 2);
 * // => [1]
 *
 * _.dropRight([1, 2, 3], 5);
 * // => []
 *
 * _.dropRight([1, 2, 3], 0);
 * // => [1, 2, 3]
 */
function dropRight(array, n, guard) {
  var length = array ? array.length : 0;
  if (!length) {
    return [];
  }
  n = (guard || n === undefined) ? 1 : toInteger(n);
  n = length - n;
  return baseSlice(array, 0, n < 0 ? 0 : n);
}

/**
 * Gets all but the last element of `array`.
 *
 * @static
 * @memberOf _
 * @category Array
 * @param {Array} array The array to query.
 * @returns {Array} Returns the slice of `array`.
 * @example
 *
 * _.initial([1, 2, 3]);
 * // => [1, 2]
 */
function initial(array) {
  return dropRight(array, 1);
}

/**
 * Checks if `value` is classified as a `Function` object.
 *
 * @static
 * @memberOf _
 * @category Lang
 * @param {*} value The value to check.
 * @returns {boolean} Returns `true` if `value` is correctly classified, else `false`.
 * @example
 *
 * _.isFunction(_);
 * // => true
 *
 * _.isFunction(/abc/);
 * // => false
 */
function isFunction(value) {
  // The use of `Object#toString` avoids issues with the `typeof` operator
  // in Safari 8 which returns 'object' for typed array and weak map constructors,
  // and PhantomJS 1.9 which returns 'function' for `NodeList` instances.
  var tag = isObject(value) ? objectToString.call(value) : '';
  return tag == funcTag || tag == genTag;
}

/**
 * Checks if `value` is the [language type](https://es5.github.io/#x8) of `Object`.
 * (e.g. arrays, functions, objects, regexes, `new Number(0)`, and `new String('')`)
 *
 * @static
 * @memberOf _
 * @category Lang
 * @param {*} value The value to check.
 * @returns {boolean} Returns `true` if `value` is an object, else `false`.
 * @example
 *
 * _.isObject({});
 * // => true
 *
 * _.isObject([1, 2, 3]);
 * // => true
 *
 * _.isObject(_.noop);
 * // => true
 *
 * _.isObject(null);
 * // => false
 */
function isObject(value) {
  var type = typeof value;
  return !!value && (type == 'object' || type == 'function');
}

/**
 * Converts `value` to an integer.
 *
 * **Note:** This function is loosely based on [`ToInteger`](http://www.ecma-international.org/ecma-262/6.0/#sec-tointeger).
 *
 * @static
 * @memberOf _
 * @category Lang
 * @param {*} value The value to convert.
 * @returns {number} Returns the converted integer.
 * @example
 *
 * _.toInteger(3);
 * // => 3
 *
 * _.toInteger(Number.MIN_VALUE);
 * // => 0
 *
 * _.toInteger(Infinity);
 * // => 1.7976931348623157e+308
 *
 * _.toInteger('3');
 * // => 3
 */
function toInteger(value) {
  if (!value) {
    return value === 0 ? value : 0;
  }
  value = toNumber(value);
  if (value === INFINITY || value === -INFINITY) {
    var sign = (value < 0 ? -1 : 1);
    return sign * MAX_INTEGER;
  }
  var remainder = value % 1;
  return value === value ? (remainder ? value - remainder : value) : 0;
}

/**
 * Converts `value` to a number.
 *
 * @static
 * @memberOf _
 * @category Lang
 * @param {*} value The value to process.
 * @returns {number} Returns the number.
 * @example
 *
 * _.toNumber(3);
 * // => 3
 *
 * _.toNumber(Number.MIN_VALUE);
 * // => 5e-324
 *
 * _.toNumber(Infinity);
 * // => Infinity
 *
 * _.toNumber('3');
 * // => 3
 */
function toNumber(value) {
  if (isObject(value)) {
    var other = isFunction(value.valueOf) ? value.valueOf() : value;
    value = isObject(other) ? (other + '') : other;
  }
  if (typeof value != 'string') {
    return value === 0 ? value : +value;
  }
  value = value.replace(reTrim, '');
  var isBinary = reIsBinary.test(value);
  return (isBinary || reIsOctal.test(value))
    ? freeParseInt(value.slice(2), isBinary ? 2 : 8)
    : (reIsBadHex.test(value) ? NAN : +value);
}

module.exports = initial;