如blockly文档的Code Generators章节里所说，用户在blockly编辑器中写好了程序之后(积木组合)，程序往往需要被转化为某一门编程语言（JavaScript, Python, PHP, Lua, Dart等），以便于执行它

比如我们在blockly开发之hello world(0)中写的这个程序

我们想运行它，以便检验你的数学能力

运行代码

分几个步骤

generate (从积木中生成代码)

原始版本

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<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
  <title>Blockly Demo: Fixed Blockly</title>
  <script src="../../blockly_compressed.js"></script>
  <script src="../../blocks_compressed.js"></script>
  <script src="../../msg/js/en.js"></script>
  <style>
    body {
      background-color: #fff;
      font-family: sans-serif;
    }
    h1 {
      font-weight: normal;
      font-size: 140%;
    }
  </style>
</head>
<body>
  <h1><a href="https://developers.google.com/blockly/">Blockly</a> &gt;
    <a href="../index.html">Demos</a> &gt; Fixed Blockly</h1>

  <p>This is a simple demo of injecting Blockly into a fixed-sized 'div' element.</p>

  <p>&rarr; More info on <a href="https://developers.google.com/blockly/guides/configure-blockly/web/fixed-size">injecting fixed-sized Blockly</a>&hellip;</p>

  <div id="blocklyDiv" style="height: 480px; width: 600px;"></div>

  <xml id="toolbox" style="display: none">
    <block type="controls_if"></block>
    <block type="logic_compare"></block>
    <block type="controls_repeat_ext"></block>
    <block type="math_number"></block>
    <block type="math_arithmetic"></block>
    <block type="text"></block>
    <block type="text_print"></block>
  </xml>

  <script>
    var demoWorkspace = Blockly.inject('blocklyDiv',
        { media: '../../media/',
          toolbox: document.getElementById('toolbox')}
        );
  </script>

</body>
</html>

增加的部分

参考: blockly/demos/generator/index.html

引入依赖

<script src="../../javascript_compressed.js"></script>

这个js文件的功能是用于生成<script src="../../blocks_compressed.js"></script>预定义的积木对应的js代码

此外通过引入其他语言模块，我们还可以将blocks_compressed.js预知的积木块生成python、Python, PHP, Lua, Dart等待

javascript_compressed.js需要在blockly_compressed.js之后被引用

生成代码

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    function showCode() {
      // Generate JavaScript code and display it.
      Blockly.JavaScript.INFINITE_LOOP_TRAP = null;
      var code = Blockly.JavaScript.workspaceToCode(demoWorkspace);
      console.log(code);
    }

运行代码

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    function runCode() {
      // Generate JavaScript code and run it.
      window.LoopTrap = 1000;
      Blockly.JavaScript.INFINITE_LOOP_TRAP =
          'if (--window.LoopTrap == 0) throw "Infinite loop.";\n';
      var code = Blockly.JavaScript.workspaceToCode(demoWorkspace);
      Blockly.JavaScript.INFINITE_LOOP_TRAP = null;
      try {
        eval(code);
      } catch (e) {
        alert(e);
      }
    }

添加按钮

添加两个按钮把事件关联起来

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  <p>
    <button onclick="showCode()">Show JavaScript</button>
    <button onclick="runCode()">Run JavaScript</button>
  </p>

完整版本

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<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
  <title>Blockly Demo: Fixed Blockly</title>
  <script src="../../blockly_compressed.js"></script>
  <script src="../../blocks_compressed.js"></script>
  <script src="../../javascript_compressed.js"></script>
  <script src="../../msg/js/en.js"></script>
  <style>
    body {
      background-color: #fff;
      font-family: sans-serif;
    }
    h1 {
      font-weight: normal;
      font-size: 140%;
    }
  </style>
</head>
<body>
  <h1><a href="https://developers.google.com/blockly/">Blockly</a> &gt;
    <a href="../index.html">Demos</a> &gt; Fixed Blockly</h1>

  <p>This is a simple demo of injecting Blockly into a fixed-sized 'div' element.</p>

  <p>&rarr; More info on <a href="https://developers.google.com/blockly/guides/configure-blockly/web/fixed-size">injecting fixed-sized Blockly</a>&hellip;</p>

  <p>
    <button onclick="showCode()">Show JavaScript</button>
    <button onclick="runCode()">Run JavaScript</button>
  </p>

  <div id="blocklyDiv" style="height: 480px; width: 600px;"></div>

  <xml id="toolbox" style="display: none">
    <block type="controls_if"></block>
    <block type="logic_compare"></block>
    <block type="controls_repeat_ext"></block>
    <block type="math_number"></block>
    <block type="math_arithmetic"></block>
    <block type="text"></block>
    <block type="text_print"></block>
  </xml>

  <script>
    var demoWorkspace = Blockly.inject('blocklyDiv',
        { media: '../../media/',
          toolbox: document.getElementById('toolbox')}
        );



    function showCode() {
      // Generate JavaScript code and display it.
      Blockly.JavaScript.INFINITE_LOOP_TRAP = null;
      var code = Blockly.JavaScript.workspaceToCode(demoWorkspace);
      console.log(code);
    }

    function runCode() {
      // Generate JavaScript code and run it.
      window.LoopTrap = 1000;
      Blockly.JavaScript.INFINITE_LOOP_TRAP =
          'if (--window.LoopTrap == 0) throw "Infinite loop.";\n';
      var code = Blockly.JavaScript.workspaceToCode(demoWorkspace);
      Blockly.JavaScript.INFINITE_LOOP_TRAP = null;
      try {
        eval(code);
      } catch (e) {
        alert(e);
      }
    }
  </script>

</body>
</html>

run

以js运行

如果你回答对了:

如果你答错了:

延伸

我最近在写一份blockly的入门和进阶教程，这个官方教程也被我纳入其中，在教程的第二节blockly_2_generate_and_run_js，目前教程以源码的形式出现:wwj718/blockly_dev，还没写成博客。大家能阅读js的话，可以自行阅读。或者等我有空补上文章。

参考