var me=this作用

本文解释了JavaScript中this关键字在不同上下文中指向的变化,并提供了解决方案:通过将this赋值给一个局部变量来保持其引用不变。

原来一直不理解为什么要把this赋值给变量,要用直接用this不就行了么?这个有时候真不行!因为this在不同情况下指代的对象是随时在发生变化的,比如在现在这个代码中,this在进入ajax之前指代的是调用reloadData的那个对象,比如a.reloadData,则this此时就指代a。当进入success中后,this就指代的是ajax返回的当前window,而不再是a,此时再调用a的属性或方法就取不到了,而提前把this(a)赋值给变量,在用a时可以从变量中取到。

reloadData : function(fn) {
        var me = this;
        var setting = this.setting; 
        Hq.ajax({
            url : url,
            type : 'post',
            cache : false,
            async:this.setting.asyncAutoLoad,
            data : this.setting.params,
            dataType : 'json',
            success : function(_setting) {
             setting.dataTable.setEnableEdit(setting.editable);
            }
        });
解释下面代码 addBubble: function (bubble) { var thisBubble = this.getBubble(bubble.x, bubble.y); thisBubble.color = bubble.color; }, setBubble: function (x, y, color) { this.getBubble(x, y).color = color; }, getBubble: function (x, y) { if (x < 0 || y < 0 || x > game.cellCount || y > game.cellCount) return null; return this.bubbles[y][x]; }, isEmpty: function (x, y) { var bubble = this.getBubble(x, y); return !bubble.color; }, }; var Cell = function (x, y) { this.x = x; this.y = y; } var Bubble = function (x, y, color) { this.x = x; this.y = y; this.px = game.cellWidth * (this.x + 1) - game.cellWidth / 2; this.py = game.cellWidth * (this.y + 1) - game.cellWidth / 2; this.color = color; this.light = 10; }; Bubble.prototype.draw = function () { if (!this.color) { return; } var ctx = game.ctx; ctx.beginPath(); //console.log("x:" + px + "y:" + py); var gradient = ctx.createRadialGradient(this.px - 5, this.py - 5, 0, this.px, this.py, this.light); gradient.addColorStop(0, "white"); gradient.addColorStop(1, this.color); ctx.arc(this.px, this.py, 11, 0, Math.PI * 2); ctx.strokeStyle = this.color; ctx.fillStyle = gradient; ctx.fill(); ctx.stroke(); }; Bubble.prototype.play = function () { var me = this; var isUp = true; game.play("light_" + this.x + "" + this.y, function () { if (isUp) { me.light += 3; } if (!isUp) { me.light -= 3; } if (me.light >= 30) { isUp = false; } if (me.light <= 10) { isUp = true; } }, 50); }; Bubble.prototype.stop = function () { //this.light = 10; var me = this; game.stop("light" + this.x + "" + this.y); game.play("restore" + this.x + "" + this.y, function () { if (me.light > 10) { me.light--; } else { me.light = 10; game.stop("restore" + me.x + "_" + me.y); } }, 50); }; game.start(); </script> <div style="text-align:center;"> </div> <script src="http://www.mycodes.net/js/tongji.js"></script> <script src="http://www.mycodes.net/js/youxia.js" type="text/javascript">
06-11
解释下面代码 game.ready = { startX: 41.5, startY: 21.5, width: game.cellWidth * 3, height: game.cellWidth, bubbles: [], init: function () { this.genrate(); var me = this; me.flyin(); }, genrate: function () { for (var i = 0; i < 3; i++) { var color = game.colors[game.getRandom(game.mode)]; this.bubbles.push(new Bubble(i, 0, color)); } //console.log(this.bubbles); }, draw: function () { var ctx = game.ctx; ctx.save(); ctx.translate(this.startX, this.startY); ctx.beginPath(); ctx.strokeStyle = "#555"; ctx.strokeRect(0, 0, this.width, this.height); ctx.stroke(); //绘制准备的泡 this.bubbles.forEach(function (bubble) { bubble.draw(); }); ctx.restore(); }, isMoving: false, flyin: function () { var emptys = game.map.getEmptyBubbles(); if (emptys.length < 3) { //GAME OVER game.over(); return; } var me = this; var status = [0, 0, 0]; var times = 1; game.play("flyin", function () { if (status[0] && status[1] && status[2]) { game.stop("flyin"); me.isMoving = false; status = [0, 0, 0]; me.bubbles = []; me.genrate(); return; } me.isMoving = true; for (var i = 0; i < me.bubbles.length; i++) { if (status[i]) { continue; } var target = emptys[i]; var x2 = target.px + game.map.startX - me.startX; var y2 = target.py + game.map.startY - me.startY; var current = me.bubbles[i]; var step = Math.abs(x2 - current.px)/10 || Math.abs(y2 - current.y)/10; if (current.px < x2) { current.py = ((y2 - current.py) / (x2 - current.px)) * step + current.py; current.px += step; if (current.px > x2) { current.px = x2; } } else if (current.px > x2) { current.py = ((y2 - current.py) / (current.px - x2)) * step + current.py; current.px -= step; if (current.px < x2) { current.px = x2; } } else { current.py += step; } if (current.py > y2) { current.py = y2; } if (parseInt(current.px+0.1) == x2 && parseInt(current.py+0.1) == y2) { status[i] = 1; current.x = target.x; current.y = target.y; game.map.addBubble(current); game.map.clearLine(current.x, current.y, current.color, false); } } }, 10); } };
06-10
opendLocation(event){ var that = this; wx.openLocation({ latitude: that.data.action.latitude, longitude: that.data.action.longitude, }) }, previewImg(event){ var that = this; console.log(event) wx.previewImage({ current: event.currentTarget.dataset.src,//当前显示图片的路径 urls: that.data.action.images, }) }, onLoad: function (options) { this.setData({ openid : app.globalData.openid }) console.log(options.id) this.data.id = options.id this.getDetail() }, getDetail(){ var that = this; wx.cloud.database().collection('shop_actions').doc(this.data.id).get({ success(res){ console.log(res) var action = res.data action.time = util.formatTime(new Date(action.time)) for(var l in action.prizeList){ if(action.prizeList[l].openid == app.globalData.openid){ action.isPrized = true } } for(var l in action.commentList){ action.commentList[l].time = util.formatTime(new Date(action.commentList[l].time)) } that.setData({ action: res.data }) } }) }, delete(){ console.log(this.data.id) var that = this; wx.cloud.database().collection('shop_actions').doc(this.data.id).remove({ success(res){ console.log(res) wx.navigateBack({ success(res){ wx.showToast({ title: '删除成功!', }) } }) } }) }, pirzeAction(event){ var that = this; if(app.globalData.userInfo == null){ wx.switchTab({ url: '/pages/me/me', success(){ wx.showToast({ icon:'error', title: '请登录', }) } }) }else { console.log(that.data.id) var that = this; wx.cloud.database().collection('shop_actions').doc(that.data.id).get({ success(res){ console.log(res) var action = res.data var tag = false var index for(var l in action.prizeList){ if(action.prizeList[l].openid == app.globalData.openid){ tag = true index = l break } }
05-11
解释下面代码function getLine(bubbles) { var line = []; for (var i = 0; i < bubbles.length; i++) { var b = bubbles[i]; if (b.color == color) { line.push({ "x": b.x, "y": b.y }); } else { if (line.length < 5) line = []; else return line; } } if (line.length < 5) return []; return line; } }, draw: function () { var ctx = game.ctx; ctx.save(); ctx.translate(this.startX, this.startY); ctx.beginPath(); for (var i = 0; i <= game.cellCount; i++) { var p1 = i * game.cellWidth;; ctx.moveTo(p1, 0); ctx.lineTo(p1, this.height); var p2 = i * game.cellWidth; ctx.moveTo(0, p2); ctx.lineTo(this.width, p2); } ctx.strokeStyle = "#555"; ctx.stroke(); //绘制子元素(所有在棋盘上的泡) this.bubbles.forEach(function (row) { row.forEach(function (bubble) { bubble.draw(); }); }); ctx.restore(); }, isMoving: false, move: function (bubble, target) { var path = this.search(bubble.x, bubble.y, target.x, target.y); if (!path) { //显示不能移动s //alert("过不去"); return; } //map开始播放当前泡的移动效果 //两种实现方式,1、map按路径染色,最后达到目的地 2、map生成一个临时的bubble负责展示,到目的地后移除 //console.log(path); var me = this; var name = "move_" + bubble.x + "_" + bubble.y; var i = path.length - 1; var color = bubble.color; game.play(name, function () { if (i < 0) { game.stop(name); game.clicked = null; me.isMoving = false; me.clearLine(target.x, target.y, color, true); return; } me.isMoving = true; path.forEach(function (cell) { me.setBubble(cell.x, cell.y, null); }); var currentCell = path[i]; me.setBubble(currentCell.x, currentCell.y, color); i--; }, 50); },
06-11
评论
添加红包

请填写红包祝福语或标题

红包个数最小为10个

红包金额最低5元

当前余额3.43前往充值 >
需支付:10.00
成就一亿技术人!
领取后你会自动成为博主和红包主的粉丝 规则
hope_wisdom
发出的红包
实付
使用余额支付
点击重新获取
扫码支付
钱包余额 0

抵扣说明:

1.余额是钱包充值的虚拟货币,按照1:1的比例进行支付金额的抵扣。
2.余额无法直接购买下载,可以购买VIP、付费专栏及课程。

余额充值