小编fis*_*ert的帖子

我遇到一个错误，即使该元素是画布，也无法调用getContext。

var canvas = document.getElementById(id);
console.log(canvas, canvas.nodeName);
var ctx = canvas.getContext('2d');

谢谢！

它的片段是独立运行的，但不能在脚本中运行

var canvas = document.getElementById(id);
console.log(canvas, canvas.nodeName);
var ctx = canvas.getContext('2d');

var canvas = document.getElementById( '0_0' );
document.write(canvas.getContext('2d'));

<canvas x=?"-8" y=?"-8" id=?"0_0">? "canvas"
Uncaught TypeError: canvas.getContext is not a function
  at Array.populateNodes (script.js:95)
  at Array.Co.call (d3.v3.min.js:3)
  at gen_graph (script.js:63)
  at Object.success (main.js:16)
  at i (jquery.min.js:2)
  at Object.fireWith [as resolveWith] (jquery.min.js:2)
  at A (jquery.min.js:4)
  at XMLHttpRequest.<anonymous> (jquery.min.js:4)

js，使用d3：

抱歉我的JS有多糟糕，我很陌生