I am working with react D3 charts, and I have created charts and it is working fine.
What I have done
Using below code to show the tooltip
.on("mousemove", function (event, d) {
// this whole code is when I hover that perticular bar
d3.select(this)
.transition()
.duration("50")
.attr("opacity", 0.6)
.attr("x", (a) => xScaleBars(a.timeline) - 3)
.attr("width", xScaleBars.bandwidth() + 6)
.style("filter", "url(#glow)");
div.transition().duration(50).style("opacity", 1);
div
.html(
`</text><text"></br> value : ${d.dataToShow}
<br/>
</text><text"></br> Month : ${d.month}
`
)
.style("left", event.pageX - 58 + "px")
.style("top", event.pageY - 140 + "px");
})
.on("mouseout", function (d, i) {
// this is when I move cursor out of that bar
d3.select(this)
.transition()
.duration("50")
.attr("width", xScaleBars.bandwidth())
.attr("x", (a) => xScaleBars(a.timeline))
.style("filter", "none")
.attr("opacity", "1");
div.transition().duration("50").style("opacity", 0);
})
Issue I am facing
The issue is when I hover over one chart component it shows the tooltip, and than when I hover over the other both shows at the same time. 
What I am trying to do is to show the tooltip when I hover the one bar of any chart and than hide it,I tried below code
d3.select("svg").selectAll(".tooltipCHart").remove();
But it doesn't resolve my issue, I think I am missing some small part
The problem is that you're creating a new tooltip div every time you re-render the chart.
A better approach is to have a hidden tooltip div in the beginning (in the render / return from your function component) and then just modify its contents and style (opacity: 1) on mouseover and mouseout. Keep track of the tooltip div using a ref.
See working codesandbox (I only modified chart1, you can make similar changes to chart2)