我想做一个有水流动的动态水管。前面的图片是错误信息。
下图是vue页面中方法中的一个方法。不知道会不会报错。如果不调用该方法，则不会报告任何内容。
以下代码是引入vue页面的js文件
//构造函数
function Createline(config) {
this.c = 0;
this.lines = [];
var self = this;
//初始化线
(function (self){
if(config.fx == "w"){
var number = config.canvas_w / (config.width + config.width/2 + config.jiange*2);
number = Math.ceil(number) + 1;
for(var n = 0 ; n < number ; n++){
var mxx = config.canvas_w - n*(config.width+config.width/2+config.jiange*2);
var lines_data = {
mx:mxx,
lx:mxx - config.width,
my:config.my,
ly:config.ly,
vx:config.vx,
vy:config.vy,
}
self.lines.push(lines_data);
var lines_data2 = {
mx:mxx-config.width-config.jiange,
lx:mxx-config.width-config.jiange-config.width/2,
my:config.my,
ly:config.ly,
vx:config.vx,
vy:config.vy,
}
self.lines.push(lines_data2);
}
}
if(config.fx == "h"){
var number = config.canvas_w / (config.width + config.width/2 + config.jiange*2);
number = Math.ceil(number) + 1;
for(var n = 0 ; n < number ; n++){
var myy = config.canvas_h - n*(config.width+config.width/2+config.jiange*2);
var lines_data3 = {
mx:config.mx,
lx:config.lx,
my:myy,
ly:myy - config.width,
vx:config.vx,
vy:config.vy,
}
self.lines.push(lines_data3);
var lines_data4 = {
mx:config.mx,
lx:config.lx,
my:myy-config.width-config.jiange,
ly:myy-config.width-config.jiange-config.width/2,
vx:config.vx,
vy:config.vy,
}
self.lines.push(lines_data4);
}
}
})(self);
}
//开始
Createline.prototype.begin = function (element,config) {
var canvasObj = document.getElementById(element);
var self = this;
var canvas = {
line_w: config.line_w || 3, //线条厚度
vx: config.vx || 0,//x轴运动速度
vy:config.vy || 0,//Y轴速度
color:config.color || "blue",//线条颜色
canvas_w:config.canvas_w || 0,//画布宽度
canvas_h:config.canvas_h || 0,//画布高度
mx: config.mx || 0,//线的开始位置X坐标
my: config.my || 0,//线的开始位置Y坐标
lx: config.lx || 0,//线的结束位置X坐标
ly: config.ly || 0,//线的结束位置Y坐标
fx:config.fx || "w",//运动方向 w 水平 ，h: 垂直
width:config.width || 20,//线的长度
jiange:config.jiange || 10, //线的间隔
}
if(canvasObj.getContext("2d")){
canvas.ctx = canvasObj.getContext("2d"),
canvasObj.width = canvas.canvas_w;
canvasObj.height = canvas.canvas_h;
}else{
console.log("当前环境不支持canvas");
return null;
}
setInterval(function(){
self.createline(self,canvas);
if(canvas.fx == "w"){
self.updateline_w(self,canvas);
}
if(canvas.fx == "h"){
self.updateline_h(self,canvas);
}
self.addline(self,canvas);
},config.time);
return canvas.ctx;
}
//画线
Createline.prototype.createline = function(self,canvas){
var content = canvas.ctx;
content.clearRect(0,0,canvas.canvas_w,canvas.canvas_h);
for(var i = 0 ; i < self.lines.length ; i++){
content.beginPath();
content.moveTo(self.lines[i].mx,self.lines[i].my);
//线经过的转折点或结束点
content.lineTo(self.lines[i].lx,self.lines[i].ly);
//线条宽度
content.lineWidth = canvas.line_w;
content.strokeStyle = canvas.color;
content.stroke();
//线条颜色
content.closePath();
//画线
}
}
//改变数据 水平运动
Createline.prototype.updateline_w = function(self,canvas){
for (var i = 0 ; i < self.lines.length ; i++) {
self.lines[i].mx = self.lines[i].mx + self.lines[i].vx;
self.lines[i].lx = self.lines[i].lx + self.lines[i].vx;
}
//超出画布的线条从数组内删除，减少系统消耗
var cnt = [];
for (var j = 0 ;j < self.lines.length ; j++) {
if(self.lines[j].lx > canvas.canvas_w){
cnt.push(j);
}
}
for(var k = 0; k < cnt.length ; k++){
self.lines.splice(k,1);
}
}
//改变数据 垂直运动
Createline.prototype.updateline_h = function(self,canvas){
for (var i = 0 ; i < self.lines.length ; i++) {
self.lines[i].my = self.lines[i].my + lines[i].vy;
self.lines[i].ly = self.lines[i].ly + lines[i].vy;
}
//超出画布的线条从数组内删除，减少系统消耗
var cnt = [];
for (var j = 0 ;j < self.lines.length ; j++) {
if( self.lines[j].ly > canvas.canvas_h){
cnt.push(j);
}
}
for(var k = 0; k < cnt.length ; k++){
self.lines.splice(k,1);
}
}
//增加线
Createline.prototype.addline = function(self,canvas){
var length = self.lines.length;
//横线
if(canvas.fx == "w"){
//判断是否需要生成线
if(self.lines[length-1].lx > 0){
//起点位置 等于 左右一根线的坐标减去间隔
var ww = self.lines[length - 1].lx - canvas.jiange;
//判断长短
if(self.c == 0){
var jg = canvas.width;
self.c = 10;
}else{
var jg = canvas.width/2;
self.c = 0;
}
var lxx = ww - jg;
var data = {
mx:ww,
lx:lxx,
my:canvas.my,
ly:canvas.ly,
vx:canvas.vx,
vy:canvas.vy,
}
self.lines.push(data);
}
}
//垂直
if(canvas.fx == "h"){
if(length>0){
//判断是否需要生成线
if(self.lines[length-1].ly > 0){
//起点位置 等于 左右一根线的坐标减去间隔
var my = self.lines[length - 1].ly - canvas.jiange;
//判断长短
if(c == 0){
var jg = canvas.width;
c = 10;
}else{
var jg = canvas.width/2;
c = 0;
}
var ly = my - jg;
var data = {
mx:canvas.mx,
lx:canvas.lx,
my:my,
ly:ly,
vx:canvas.vx,
vy:canvas.vy,
}
self.lines.push(data);
}
}else{
var data = {
mx:canvas.mx,
my:canvas.my,
lx:canvas.lx,
ly:canvas.ly,
vx:canvas.vx,
vy:canvas.vy,
}
self.lines.push(data);
}
}
}
export{
Createline
}
最佳答案
在为使用 this 的构造函数创建实例时，需要使用 new:
var cre = new Createline(data);
当使用 new 执行函数时，它会执行以下操作:
function User(name) {
// this = {}; (implicitly)
// add properties to this
this.name = name;
this.isAdmin = false;
// return this; (implicitly)
}
关于javascript - vue 显示 js 's error :TypeError: "这是未定义的”，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/58586272/