ChartJS Unix Time Values changed - vuejs2

Question

I'm importing data from a Sybase database into ChartJS in VueJs2. I'm using the vue-chart module
I push the timestamps into an array as Unix times using
this.firstIn(new Date(tnaDetails[0].Sunday_FirstIn).getTime())
So:
[Sunday_FirstIn:2010-01-17 08:00:00.0]
Would convert to
1263708000000
Which I then add to the dataset:
datasets: [{
type: 'line',
label: "First In",
backgroundColor: "green",
data: this.firstIn,
fill: false
}
]
However, when the data is plotted on the graph, the values are changed. The above Unit Timestamp becomes
1263700000000
Which obviously returns the wrong time. I'm not doing anything to the ticks in the options.
Below is a result of the numbers being changed. The console has the original data:
Is there a setting that alters the precision/values of numbers in ChartJS that I'm not aware of?
Thanks.
Seth

Answer 1

For anyone who has any similar problem in future, I patched together a few solutions I found.
Firstly, from here Unix Timestamp in JavaScript, I wrote the method:
getTimeString: function(dateString) {
var hours = new Date(dateString).getHours();
var mins = new Date(dateString).getMinutes();
return Math.round((new Date("1970-02-01 " + hours + ":" + mins)).getTime());
}
The important part here is to make sure you have the same day. Not doing this will cause the ChartJS graph to plot the times in different places on the y-axis, even if the hours are the same.
Then from this StackOverFlow question and the related plunker, in the chart options, I have:
{
responsive: true,
maintainAspectRatio: false,
scales: {
yAxes: [{
position: 'left',
ticks: {
callback: value => {
let date = moment(value);
if (date.diff(moment('1970-02-01 23:59:59'), 'minutes') === 0) {
return null;
}
return date.format('H:mm');
},
stepSize: 3.6e+6
}
}]
}, //end scales
tooltips: {
callbacks: {
label: function(toolTipItem, data) {
let date = moment(toolTipItem.yLabel);
if (date.diff(moment('1970-02-01 23:59:59'), 'minutes') === 0) {
return null;
}
return date.format('H:mm');
}
}
}
}
Pay attention to the callbacks. They will format the time, calculating the difference from a set time to the time you need plotted. In the first function, you could really use any day, it wouldn't matter, as long as it's the same day. The stepSize will display hourly intervals on the yAxis.