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I don't seem to be able to figure this out by reading the docs.
Is there a way to implement a onClick event handler for any of my marks?
666
Since Vega-Lite does not yet have support for signals, you could patch the generated Vega. You can add a signal to the compiled Vega spec and then add a signal listener through the Vega view API. You can patch the generated Vega with the patch option in Vega-Embed.
<!DOCTYPE html>
<head>
<meta charset="utf-8">
<script src="https://cdn.jsdelivr.net/npm/vega@5"></script>
<script src="https://cdn.jsdelivr.net/npm/vega-lite@3"></script>
<script src="https://cdn.jsdelivr.net/npm/vega-embed@4"></script>
</head>
<body>
<div id="vis"></div>
<script>
const spec = {
"$schema": "https://vega.github.io/schema/vega-lite/v3.json",
"data": {
"values": [
{"a": "A", "b": 28},
{"a": "B", "b": 55},
{"a": "C", "b": 43},
{"a": "D", "b": 91},
{"a": "E", "b": 81},
{"a": "F", "b": 53},
{"a": "G", "b": 19},
{"a": "H", "b": 87},
{"a": "I", "b": 52}
]
},
"mark": "bar",
"encoding": {
"x": {"field": "a", "type": "ordinal"},
"y": {"field": "b", "type": "quantitative"}
}
};
vegaEmbed('#vis', spec, {
patch: (spec) => {
spec.signals.push({
"name": "barClick",
"value": 0,
"on": [{"events": "rect:mousedown", "update": "barClick + 1"}]
})
return spec;
}
}).then(result => {
result.view.addSignalListener('barClick', console.log);
}).catch(console.warn);
</script>
</body>
I had a hard time with vega-lite to get the patch to recognize the objects I wanted click events for. So instead, I just added a generic eventListener
vegaEmbed('#vis', spec, {}
).then(result => {
result.view.addEventListener('click', function(event, item) {
console.log('CLICK', event, item);
});
}).catch(console.warn);
The item object contains the datum. If there is no datum, you know the click was not on a useful location.
https://vega.github.io/vega/docs/api/view/#view_addEventListener
21
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