Changing color when node is selected in Cytoscape JS

Question

I would like to change the color of a selected node to a different color than the predefined background-color. However, as soon as I define a background color for the node in "style", the color does not change to blue (default behavior).

Here is the style I have defined:

selector: 'node',
style: {
    'content': 'data(d2)',
    'background-color': '#ccc',
}

Can someone help? Lazloo

score 8 · Accepted Answer · answered Jan 27 '20 at 07:26

This is a fairly simple thing for cytoscape.js and I would recommend you to look at some of the examples provided in the docs.

The important part here is the :selected state, which any component has if it has been selected by a click. You can address this state in your stylesheet and add any styles you want. You can also bind this on cy.on() and add the style with cy.element(...).style().

In general, I would suggest adding a style to the cytoscape-stylesheet:

var cy = window.cy = cytoscape({
  container: document.getElementById('cy'),

  style: [{
      selector: 'node',
      css: {
        'content': 'data(id)',
        'text-valign': 'center',
        'text-halign': 'center',
        'height': '60px',
        'width': '60px'
      }
    },
    {
      selector: ':selected',
      css: {
        'background-color': 'SteelBlue',
        'line-color': 'black',
        'target-arrow-color': 'black',
        'source-arrow-color': 'black'
      }
    }
  ],

  elements: {
    nodes: [{
        data: {
          id: 'n0'
        }
      },
      {
        data: {
          id: 'n1'
        }
      },
      {
        data: {
          id: 'n2'
        }
      },
      {
        data: {
          id: 'n3'
        }
      },
      {
        data: {
          id: 'n4'
        }
      },
      {
        data: {
          id: 'n5'
        }
      },
      {
        data: {
          id: 'n6'
        }
      },
      {
        data: {
          id: 'n7'
        }
      },
      {
        data: {
          id: 'n8'
        }
      },
      {
        data: {
          id: 'n9'
        }
      },
      {
        data: {
          id: 'n10'
        }
      },
      {
        data: {
          id: 'n11'
        }
      },
      {
        data: {
          id: 'n12'
        }
      },
      {
        data: {
          id: 'n13'
        }
      },
      {
        data: {
          id: 'n14'
        }
      },
      {
        data: {
          id: 'n15'
        }
      },
      {
        data: {
          id: 'n16'
        }
      }
    ],
    edges: [{
        data: {
          source: 'n0',
          target: 'n1'
        }
      },
      {
        data: {
          source: 'n1',
          target: 'n2'
        }
      },
      {
        data: {
          source: 'n1',
          target: 'n3'
        }
      },
      {
        data: {
          source: 'n2',
          target: 'n7'
        }
      },
      {
        data: {
          source: 'n2',
          target: 'n11'
        }
      },
      {
        data: {
          source: 'n2',
          target: 'n16'
        }
      },
      {
        data: {
          source: 'n3',
          target: 'n4'
        }
      },
      {
        data: {
          source: 'n3',
          target: 'n16'
        }
      },
      {
        data: {
          source: 'n4',
          target: 'n5'
        }
      },
      {
        data: {
          source: 'n4',
          target: 'n6'
        }
      },
      {
        data: {
          source: 'n6',
          target: 'n8'
        }
      },
      {
        data: {
          source: 'n8',
          target: 'n9'
        }
      },
      {
        data: {
          source: 'n8',
          target: 'n10'
        }
      },
      {
        data: {
          source: 'n11',
          target: 'n12'
        }
      },
      {
        data: {
          source: 'n12',
          target: 'n13'
        }
      },
      {
        data: {
          source: 'n13',
          target: 'n14'
        }
      },
      {
        data: {
          source: 'n13',
          target: 'n15'
        }
      },
    ]
  },

  layout: {
    name: 'dagre',
    padding: 5
  }
});

body {
  font: 14px helvetica neue, helvetica, arial, sans-serif;
}

#cy {
  height: 100%;
  width: 100%;
  position: absolute;
  left: 0;
  top: 0;
  float: left;
}

<html>

<head>
  <script src="https://unpkg.com/cytoscape/dist/cytoscape.min.js"></script>
  <script src="https://unpkg.com/dagre@0.7.4/dist/dagre.js"></script>
  <script src="https://cdn.jsdelivr.net/npm/cytoscape-dagre@2.1.0/cytoscape-dagre.min.js"></script>
</head>

<body>
  <div id="cy"></div>
</body>

</html>

Thanks for the answer, but note that I had the same question while staring right at the docs and reading them pretty thoroughly. There is no mention of **:selection** on the [styling docs](https://dash.plotly.com/cytoscape/styling) I am reading. Perhaps a better answer is that the *dash.plotly docs* are missing a lot of detail and one needs to also read the *js.cytoscape.org* docs (even though I'm writing python??) — Paul Cuddihy, Mar 27 '23 at 13:08
Found it in the dash.plotly docs '''Both the selector string and the style dictionary are exhaustively documented in the Cytoscape.js docs.''' with links that are slightly obscured by the styling of the docs. — Paul Cuddihy, Mar 27 '23 at 13:25

Changing color when node is selected in Cytoscape JS

1 Answers1