Add _.toSafeInteger.

lodash.js

@@ -9771,6 +9771,33 @@
       return copyObject(value, keysIn(value));
     }
 
+    /**
+     * Converts `value` to a safe integer. A safe integer can be compared and
+     * represented correctly.
+     *
+     * @static
+     * @memberOf _
+     * @category Lang
+     * @param {*} value The value to convert.
+     * @returns {number} Returns the converted integer.
+     * @example
+     *
+     *  _.toSafeInteger('3.14');
+     *  // => 3
+     *
+     * _.toSafeInteger(NaN);
+     * // => 0
+     *
+     * _.toSafeInteger(Infinity)
+     * // => 9007199254740991
+     *
+     * _.toSafeInteger(-Infinity)
+     * // => -9007199254740991
+     */
+    function toSafeInteger(value) {
+      return clamp(toInteger(value), -MAX_SAFE_INTEGER, MAX_SAFE_INTEGER);
+    }
+
     /**
      * Converts `value` to a string if it's not one.
      * An empty string is returned for `null` and `undefined` values.
@@ -13102,6 +13129,7 @@
     lodash.template = template;
     lodash.toInteger = toInteger;
     lodash.toLower = toLower;
+    lodash.toSafeInteger = toSafeInteger;
     lodash.toString = toString;
     lodash.toUpper = toUpper;
     lodash.trim = trim;

test/test.js

@@ -19170,6 +19170,29 @@
 
   /*--------------------------------------------------------------------------*/
 
+  QUnit.module('lodash.toSafeInteger');
+
+  (function() {
+    QUnit.test('should convert values to safe integers', function(assert) {
+      assert.expect(6);
+
+      assert.strictEqual(_.toSafeInteger(-5.6), -5);
+      assert.strictEqual(_.toSafeInteger('5.6'), 5);
+      assert.strictEqual(_.toSafeInteger(), 0);
+      assert.strictEqual(_.toSafeInteger(NaN), 0);
+      assert.strictEqual(_.toSafeInteger(Infinity), MAX_SAFE_INTEGER);
+      assert.strictEqual(_.toSafeInteger(-Infinity), -MAX_SAFE_INTEGER);
+    });
+
+    QUnit.test('should support `value` of `-0`', function(assert) {
+      assert.expect(1);
+
+      assert.strictEqual(1 / _.toSafeInteger(-0), -Infinity);
+    });
+  }());
+
+  /*--------------------------------------------------------------------------*/
+
   QUnit.module('lodash.transform');
 
   (function() {
@@ -21511,6 +21534,7 @@
       'sum',
       'toInteger',
       'toLower',
+      'toSafeInteger',
       'toString',
       'toUpper',
       'trim',
@@ -21762,7 +21786,7 @@
     var acceptFalsey = lodashStable.difference(allMethods, rejectFalsey);
 
     QUnit.test('should accept falsey arguments', function(assert) {
-      assert.expect(260);
+      assert.expect(261);
 
       var emptyArrays = lodashStable.map(falsey, lodashStable.constant([]));