color opacitiy based on value

[Dev C]

In my D3jS 5 I am using color opacity based on blue color but sometime values like 0 and 1, I can not see much difference, here is the code I have.

.append("rect")

.attr("x", (d) => this.xScale(d.day))

.attr("y", (d) => this.yScale(d.time))

.attr("width", this.xScale.bandwidth())

.attr("height", this.yScale.bandwidth())

.on("mouseover", this.mouseOverHandler)

.on("mouseleave", this.mouseLeaveHandler)

.style("fill", "white")

.transition(t)

.delay((d, i) => i * 20)

.style("fill", (d) => this.colorRange(d.value));

and defined colorRange:{} and assigned as below:

this.colorRange = d3

.scaleLinear()

.range(["#B7C0FC", "#216BFF"])

.domain([1, 1000]);

},

Anybody can help me on what basis color can be differentiated if values are like 0 and 1