fix

book/node_modules/array-difference/difference.js

@@ -0,0 +1,46 @@
+(function(global) {
+
+	var indexOf = Array.prototype.indexOf || function(elem) {
+		var idx, len;
+
+		if (this == null) {
+			throw new TypeError("indexOf called on null or undefined");
+		}
+
+		for (idx = 0, len = this.length; idx < len; ++idx) {
+			if (this[idx] === elem) {
+				return idx;
+			}
+		}
+
+		return -1;
+	};
+
+	function difference(a, b) {
+		var idx, len;
+		var res = [];
+
+		for (idx = 0, len = a.length; idx < len; ++idx) {
+			if (indexOf.call(b, a[idx]) === -1) {
+				res.push(a[idx]);
+			}
+		}
+		for (idx = 0, len = b.length; idx < len; ++idx) {
+			if (indexOf.call(a, b[idx]) === -1) {
+				res.push(b[idx]);
+			}
+		}
+		return res;
+	}
+
+	if (typeof module === "object" && module.exports) {
+		module.exports = difference;
+	} else if (typeof define === "function" && define.amd) {
+		define(function() {
+			return difference;
+		});
+	} else {
+		global.difference = difference;
+	}
+
+}(this));