Can we add event listeners to “Vega-Lite” specification?

Question

I am new to Vega and Vega-Lite. I am creating a simple bar chart using Vega-Lite but I am not able to add any event listeners e.g. "hover".

I want to hover a bar and change the color of the bar.

Answer 1

If you're using Vega-Embed, it returns a promise with a reference to the view which allows you to use addEventListener - explained in the docs here.

Here is an example:

const width = 600
const color = blue
embed(element, {
    $schema: 'https://vega.github.io/schema/vega-lite/3.0.0-rc6.json',
    data: { 'values': data },
    mark: {
        type: 'line',
        color,
        point: {
            color,
        }
    },
    width,
    height: width / 2,
    encoding: {
        'x': {
            field: 'label',
            type: 'temporal',
        },
        'y': {
            field: 'value',
            type: 'quantitative',
        },
    }
}).then(({spec, view}) => {
    view.addEventListener('mouseover', function (event, item) {
        console.log(item.datum)
    })
})