javascript - Try to implement shooting by bullets -

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hello try implement shooting drawing bullets. created function shoot , called keyboard detection condition.... however, when press key shoot stopped , no shooting, no bullets....whats happening?! appreciated thanks.

<html>   <head>     <title>spaceman invaders</title>    <script>    window.onload = function() {     var posx = 20;     var posy = 0;     var go_right = true;     var go_down = false;          var canvas = document.getelementbyid("screen");         context = canvas.getcontext("2d");         context2 = canvas.getcontext("2d");       var alien = function(x, y) {         this.x = x;         this.y = y;         this.posx = 30 + x*30;         this.posy = 90 + y*30;         this.go_right = true;         this.go_down = false;     }         function player() {         this.x=0, this.y = 0, this.w = 20, this.h = 20;         this.render = function (){             context.fillstyle = "orange";             context.fillrect(this.x, this.y, this.w, this.h);          }       }                         var x2=223;        var y2=320;        function shoot(){         context2.fillstyle = "white";         context2.fillrect = (x2, y2--, 5,10);         context2.fillstyle = "yellow";         context2.fillrect = (x2, y2, 5,10);         if (y2>=0) {                 timer=settimeout("shoot()", 5);             }        }        var player = new player();     alien.prototype.move = function() {              if (!this.go_down) {                 if(this.posx + (2-this.x) * 30 < 250 && this.go_right) {                     this.posx += 3;                 } else if(this.posx < 30 + this.x*30) {                     this.go_right = true;                     this.go_down = true;                 } else if(!this.go_right) {                     this.posx -= 3;                 } else {                     this.go_right = false;                     this.go_down = true;                 }             } else {                 //if(posy <= 30)                 this.posy += 30;                 this.go_down = false;             }     }      alien.prototype.draw = function(context) {         if(this.x == 0) {             context.fillstyle = "red";         } else if(this.x == 1) {             context.fillstyle = "yellow";         } else {             context.fillstyle = "blue";         }         context.beginpath();         context.fillrect(this.posx, this.posy, 20 , 20);         context.fill();     }          var canvas = document.getelementbyid("screen");         context = canvas.getcontext("2d");          if (canvas.getcontext) {              //init aliens array             var aliens = [];             for(var = 0; < 3; i++) {                 for(var j = 0; j < 3; j++) {                     aliens.push(new alien(j, i));                 }             }              player.x=100;             player.y= 480;             setinterval( function() {                 context.fillstyle="black";                 context.fillrect(0,0,canvas.width, canvas.height);                 /*context.fillstyle = "white";                 context.fillrect(100, 460, 30 , 30);*/                  player.render();                  //move aliens & draw aliens                 for(var = 0; < 9; i++) {                     aliens[i].move(),                     aliens[i].draw(context);                 }             }, 20);             document.addeventlistener('keydown', function(event){                 var key_press = string.fromcharcode(event.keycode);                // alert(event.keycode + " | " + key_press);                  if (key_press == "d") {                         if (player.x >=(280)){                                player.x=(280);                          }                         else {                            player.x +=3;                         }                        } else                  if (key_press=="a"){                             if (player.x<0){                                 player.x=(0);                             }                             else {player.x -=3;}                         } else                          if (key_press="w") {                             //alert("pah-pah");                             shoot();                          }               });         }    };    </script>   </head>   <body>   <canvas id="screen" width="300" height="500"/>      </body> </html>

in shoot() function, you're setting fillrect parameters you're meaning pass fillrect().

function shoot(){     context2.fillstyle = "white";     //context2.fillrect = (x2, y2--, 5,10);  -- bad line. correct:     context2.fillrect(x2, y2--, 5,10);     context2.fillstyle = "yellow";     //context2.fillrect = (x2, y2, 5,10);    -- bad line. correct:     context2.fillrect(x2, y2, 5,10);      if (y2>=0) {        timer=settimeout("shoot()", 5);     }  }

has weird behavior, , there's lot improved , cleaned here, should on right track.

and future reference, if you're using chrome, open dev tools (ctrl/cmd + shift + j) , see error:

uncaught typeerror: property 'fillrect' of object #<canvasrenderingcontext2d> not function

that clued me in know getting overwritten somewhere, know function of canvasrenderingcontext2d.


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