Bump to v4.0.0.

isSafeInteger.js

@@ -0,0 +1,36 @@
+define(['./isInteger'], function(isInteger) {
+
+  /** Used as references for various `Number` constants. */
+  var MAX_SAFE_INTEGER = 9007199254740991;
+
+  /**
+   * Checks if `value` is a safe integer. An integer is safe if it's an IEEE-754
+   * double precision number which isn't the result of a rounded unsafe integer.
+   *
+   * **Note:** This method is based on [`Number.isSafeInteger`](https://mdn.io/Number/isSafeInteger).
+   *
+   * @static
+   * @memberOf _
+   * @category Lang
+   * @param {*} value The value to check.
+   * @returns {boolean} Returns `true` if `value` is a safe integer, else `false`.
+   * @example
+   *
+   * _.isSafeInteger(3);
+   * // => true
+   *
+   * _.isSafeInteger(Number.MIN_VALUE);
+   * // => false
+   *
+   * _.isSafeInteger(Infinity);
+   * // => false
+   *
+   * _.isSafeInteger('3');
+   * // => false
+   */
+  function isSafeInteger(value) {
+    return isInteger(value) && value >= -MAX_SAFE_INTEGER && value <= MAX_SAFE_INTEGER;
+  }
+
+  return isSafeInteger;
+});