D3: Add data value labels to multi line graph

Question

I am using this multiline graph but so far have failed to generate data value labels on every tick (for every day).

Answer 1

Your text will not be visible, as it is located outside the boundaries of your svg: you added a group that is translated of margin.left, and the put your x at width+3, which means located at width+3+margin.left of the left border of your svg.

Try replacing your append text with something like:

svg.append("text")
    .attr("transform", "translate(" + (width/2) + "," + y(data[0].sev4) + ")")
    .attr("dy", ".35em")
    .attr("text-anchor", "start")
    .style("fill", "red")
    .text("Sev4");

svg.append("text")
    .attr("transform", "translate(" + (width/2) + "," + y(data[0].sev3) + ")")
    .attr("dy", ".35em")
    .attr("text-anchor", "start")
    .style("fill", "steelblue")
    .text("Sev3");

I did not test it, so I cannot guarantee, but your code seems fine, that's the only thing I see.

Result of this add:

EDIT

After your clarifications, here is a plunk: http://plnkr.co/edit/lDlseqUQQXgoFwTK5Aop?p=preview

The part you will be interested in is:

svg.append('g')
.classed('labels-group', true)
.selectAll('text')
.data(data)
.enter()
.append('text')
.classed('label', true)
.attr({
  'x': function(d, i) {
    return x(d.date);
  },
  'y': function(d, i) {
    return y(d.sev3);
  }
})
.text(function(d, i) {
  return d.sev3;
});

This will draw your labels. Is it the result you try to achieve?