score:0

the onanimationprogress has 2 parameters easedecimal and stepdecimal that you can use

var mylinechart = new chart(ctx).line(data, {
    onanimationprogress: function (easedecimal, stepdecimal) {
        // stepdecimal proceeds uniformly from 0 to 1
        // easedecimal proceeds depending on the easing function from 0 to 1
        console.log(stepdecimal)
    }
});

for instance, to change the fillcolor - here i just adjust the transparency

var mylinechart = new chart(ctx).line(data, {
    animationsteps: 200,
    onanimationprogress: function (easedecimal, stepdecimal) {
        this.datasets[0].fillcolor = "rgba(120,120,120," + stepdecimal + ")";
    }
});

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