看书练习备忘

xjchenhao · xjchenhao · commit 6527f45a72e9 · 2015-07-04T09:30:20.000+08:00
diff --git a/memo/uncurrying.js b/memo/uncurrying.js
@@ -0,0 +1,53 @@
+//Function.prototype.uncurrying = function () {
+//    var self = this;    // self此时是Array.prototype.push
+//    return function () {
+//        var obj = Array.prototype.shift.call(arguments);
+//        // obj是{
+//        //    length:1,
+//        //    0:1
+//        // }
+//        // arguments对象的第一个元素被截去,剩下[2]
+//        return self.apply(obj, arguments);
+//    }
+//};
+
+// uncurrying的另外一种实现方式
+Function.prototype.uncurrying = function () {
+    var self = this;
+    return function () {
+        Function.prototype.call.apply(self, arguments);
+
+        //可以剖析成下面的方式来读:
+        //Function.prototype.call(Array.prototype.push, arguments);
+        //Array.prototype.push.call(obj = { length: 1, 0: 1}, 2);
+    }
+};
+
+var push = Array.prototype.push.uncurrying(),
+    objA = {
+        length: 1,
+        0: 1
+    };
+push(objA, 2);
+console.log(objA);   // { '0': 1, '1': 2, length: 2 }
+
+//给array对象拓展多个数组方法
+for (var i = 0, fn, ary = ['push', 'shift', 'forEach']; fn = ary[i++];) {
+    Array[fn] = Array.prototype[fn].uncurrying();
+}
+var objB = {
+    length: 3,
+    0: 1,
+    1: 2,
+    2: 3
+};
+Array.push(objB, 4);  // 向数组添加一个元素
+console.log(objB.length);    // 4
+
+var first = Array.shift(objB);
+console.log(first); // undefined    WHY?????
+console.log(objB);  // { '0': 2, '1': 3, '2': 4, length: 3 }
+
+Array.forEach(objB, function (i, n) {
+    console.log(n);  // 分别输出:0,1,2
+});
diff --git a/memo/函数节流.js b/memo/函数节流.js
@@ -0,0 +1,29 @@
+var throttle = function (fn, interval) {
+    var __self = fn,    // 保存需要被延迟执行的函数引用
+        timer,  // 定时器
+        firstTime = true;   // 是否是第一次调用
+
+    return function () {
+        var args = arguments,
+            __me = this;
+
+        if (firstTime) {    // 如果是第一次调用,不需要延迟执行
+            __self.apply(__me, arguments);
+            return firstTime = false;
+        }
+
+        if (timer) {
+            return false;
+        }
+
+        timer = setTimeout(function () {    //延迟一段时间执行
+            clearTimeout(timer);
+            timer = null;
+            __self.apply(__me, args);
+        }, interval || 500)
+    }
+};
+
+window.onresize = throttle(function () {
+    console.log(1);
+}, 500);
diff --git a/memo/分时函数.js b/memo/分时函数.js
@@ -0,0 +1,38 @@
+var timeChunk = function (ary, fn, count) {
+
+    var obj,
+        t;
+
+    var len = ary.length;
+
+    var start = function () {
+        for (var i = 0; i < Math.min(count || 1, ary.length); i++) {
+            obj = ary.shift();
+            fn(obj);
+        }
+    };
+
+    return function () {
+        t = setInterval(function () {
+            if (len === 0) {
+                return clearInterval(t);
+            }
+            start();
+        }, 200);
+    };
+
+};
+
+var ary = [];
+
+for (var i = 1; i <= 1000; i++) {
+    ary.push(i);
+}
+
+var renderFriendList = timeChunk(ary, function (n) {
+    var div = document.createElement('div');
+    div.innerHTML = n;
+    document.body.appendChild(div);
+}, 8);
+
+renderFriendList();
