javascript electron blockly google-blockly

Blockly doesn't show anything in the browser

I want to customize blockly but after following instructions from online sources, I don't see anything appearing in the browser.

This is the example code:

<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Blockly test</title>
  <!-- core library -->
  <script src="https://unpkg.com/blockly/blockly.min.js"></script>
</head>

<body>
  <div id="editor"></div>
  <xml id="toolbox">
    <block type="controls_if"></block>
    <block type="controls_repeat_ext"></block>
    <block type="logic_compare"></block>
    <block type="math_number"></block>
    <block type="math_arithmetic"></block>
    <block type="text"></block>
    <block type="text_print"></block>
  </xml>

  <script>
    Blockly.Blocks['constant_value'] = {
      init: function () {
        this.appendValueInput('VALUE')
          .setCheck('String')
          .appendField('TEST');
        this.setOutput(true, 'Number');
        this.setColour(160);
        this.setTooltip('Returns number of letters in the provided text.');
        this.setHelpUrl('http://www.w3schools.com/jsref/jsref_length_string.asp');
      }
    }
    var workspacePlayground = Blockly.inject('editor',
      { toolbox: document.getElementById('toolbox') });
  </script>
</body>

</html>

How can I make the Blockly editor show up?

Solution

Your Blockly workspace seems fine. The problem is missing CSS to give the editor a height and width so that it's visible:

<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Blockly test</title>
  <!-- core library -->
  <script src="https://unpkg.com/blockly/blockly.min.js"></script>
  
  <!-- add CSS to give the editor dimensions -->
  <style>
  #editor {
    width: 100%;
    height: 500px;
  }
  </style>
</head>

<body>
  <div id="editor"></div>
  <xml id="toolbox">
    <block type="controls_if"></block>
    <block type="controls_repeat_ext"></block>
    <block type="logic_compare"></block>
    <block type="math_number"></block>
    <block type="math_arithmetic"></block>
    <block type="text"></block>
    <block type="text_print"></block>
  </xml>

  <script>
    Blockly.Blocks['constant_value'] = {
      init: function () {
        this.appendValueInput('VALUE')
          .setCheck('String')
          .appendField('TEST');
        this.setOutput(true, 'Number');
        this.setColour(160);
        this.setTooltip('Returns number of letters in the provided text.');
        this.setHelpUrl('http://www.w3schools.com/jsref/jsref_length_string.asp');
      }
    }
    var workspacePlayground = Blockly.inject('editor',
      { toolbox: document.getElementById('toolbox') });
  </script>
</body>

</html>

All I added was:

  <style>
  #editor {
    width: 100%;
    height: 500px;
  }
  </style>