首頁(yè) 猿問我寫的這段代碼怎么不能再瀏覽器中顯...

我寫的這段代碼怎么不能再瀏覽器中顯示不出效果，請(qǐng)幫我看一下我錯(cuò)在哪里，謝謝！

JavaScript

慕粉3215732 2016-04-17 22:22:42

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8" /><title>無(wú)標(biāo)題文檔</title><script>?? ?window.onload=function(){?? ??? ?var canvas=document.getElementById("canvas");?? ??? ?if(canvas.getContext("2d")){?? ??? ??? ?var context=canvas.getContext("2d");?? ??? ?}else{?? ??? ??? ?alert("當(dāng)前瀏覽器不支持canvas,請(qǐng)更換瀏覽器后再試！");?? ??? ?}?? ??? ?var tangram=[?? ??? ??? ?{p:[{x:0,y:0},{x:800,y:0},{x:400,y:400}],color:"#caff67"},?? ??? ??? ?{p:[{x:0,y:0},{x:400,y:400},{x:0,y:800}],color:"#67becf"},?? ??? ??? ?{p:[{x:800,y:0},{x:800,y:400},{x:600,y:600},{x:600,y:200}],color:"#ef3d61"},?? ??? ??? ?{p:[{x:600,y:200},{x:600,y:600},{x:400,y:400}],color:"#f9f51a"},?? ??? ??? ?{p:[{x:400,y:400},{x:600,y:600},{x:400,y:800},{x:200,y:600}],color:"#594c0"},?? ??? ??? ?{p:[{x:200,y:600},{x:400,y:800},{x:0,y:800}],color:"#fa8ecc"},?? ??? ??? ?{p:[{x:800,y:400},{x:800,y:800},{x:400,y:800}],color:"#f6ca29"}?? ??? ?];?? ??? ?window.onload=function(){?? ??? ??? ?var canvas=document.getElementById("canvas");?? ??? ??? ?canvas.width=800;?? ??? ??? ?canvas.height=800;?? ??? ??? ?var context=canvas.getContext("2d");?? ??? ??? ?for(var i=0;i<tangram.length;i++){?? ??? ??? ??? ?draw(tangram[i],context);?? ??? ??? ?}?? ??? ?}?? ??? ?function draw(piece,cxt){?? ??? ??? ?cxt.beginPath();?? ??? ??? ?cxt.moveTo(piece.p[0].x,piece.p[0].y);?? ??? ??? ?for(var i=1;i<piece.p.length;i++){?? ??? ??? ??? ?cxt.lineTo(piece.p[i].x,piece.p[i].y);?? ??? ??? ?}?? ??? ??? ?cxt.closePath();?? ??? ??? ?cxt.fillStyle=piece.color;?? ??? ??? ?cxt.fill();?? ??? ?}?? ?}</script> </head><body>?? ?<canvas id="canvas" width="1024" height="768" style="border:1px solid #aaa;display:block;margin:50px auto;"></canvas></body></html>

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1 回答

李曉健

TA貢獻(xiàn)1036條經(jīng)驗(yàn) 獲得超461個(gè)贊

?window.onload=function(){
????????????var?canvas=document.getElementById("canvas");
????????????canvas.width=800;
????????????canvas.height=800;
????????????var?context=canvas.getContext("2d");
????????????for(var?i=0;i<tangram.length;i++){
????????????????draw(tangram[i],context);
????????????}
????????}

這里多寫了一層 window.onload，因?yàn)槟闵厦嬉呀?jīng)有了一層，所以這層不必要了,應(yīng)該是

window.onload=function(){
????var?canvas=document.getElementById("canvas");
????if(canvas.getContext("2d")){
????????var?context=canvas.getContext("2d");
????}else{
????????alert("當(dāng)前瀏覽器不支持canvas,請(qǐng)更換瀏覽器后再試！");
????}
????var?tangram=[
????????{p:[{x:0,y:0},{x:800,y:0},{x:400,y:400}],color:"#caff67"},
????????{p:[{x:0,y:0},{x:400,y:400},{x:0,y:800}],color:"#67becf"},
????????{p:[{x:800,y:0},{x:800,y:400},{x:600,y:600},{x:600,y:200}],color:"#ef3d61"},
????????{p:[{x:600,y:200},{x:600,y:600},{x:400,y:400}],color:"#f9f51a"},
????????{p:[{x:400,y:400},{x:600,y:600},{x:400,y:800},{x:200,y:600}],color:"#594c0"},
????????{p:[{x:200,y:600},{x:400,y:800},{x:0,y:800}],color:"#fa8ecc"},
????????{p:[{x:800,y:400},{x:800,y:800},{x:400,y:800}],color:"#f6ca29"}
????];
????var?canvas=document.getElementById("canvas");
????canvas.width=800;
????canvas.height=800;
????var?context=canvas.getContext("2d");
????for(var?i=0;i<tangram.length;i++){
????????draw(tangram[i],context);
????}
????function?draw(piece,cxt){
????????cxt.beginPath();
????????cxt.moveTo(piece.p[0].x,piece.p[0].y);
????????for(var?i=1;i<piece.p.length;i++){
????????????cxt.lineTo(piece.p[i].x,piece.p[i].y);
????????}
????????cxt.closePath();
????????cxt.fillStyle=piece.color;
????????cxt.fill();
????}
}

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