问题
I can't seem to get Chart.js to work with dates. I have tried quite a few different methods:
let examChart = document.getElementById("examChart").getContext("2d");
let examLineChart = new Chart(examChart, {
type: "line",
data: [
{ t: new Date("2015-3-15 13:3"), y: 12 },
{ t: new Date("2015-3-25 13:2"), y: 21 },
{ t: new Date("2015-4-25 14:12"), y: 32 }
],
options: {
label: "placeholder"
}
});
And:
let examChart = document.getElementById("examChart").getContext("2d");
let examLineChart = new Chart(examChart, {
type: "line",
data: [
{ t: "2015-3-15 13:3", y: 12 },
{ t: "2015-3-25 13:2", y: 21 },
{ t: "2015-4-25 14:12", y: 32 }
],
options: {
label: "placeholder"
}
});
And:
let examChart = document.getElementById("examChart").getContext("2d");
let examLineChart = new Chart(examChart, {
type: "line",
data: [
{ t: "Sun Mar 15 2015 12:03:45 GMT+0000 (GMT Standard Time)", y: 12 },
{ t: "Wed Mar 25 2015 12:02:15 GMT+0000 (GMT Standard Time)", y: 21 },
{ t: "Sat Apr 25 2015 13:12:30 GMT+0100 (GMT Daylight Time)", y: 32 }
],
options: {
label: "placeholder"
}
});
To cover just a few of my attempts, I just can't seem to get how to set dates properly even after reading the documentation (http://www.chartjs.org/docs/latest/axes/cartesian/time.html) (they don't actually give an example)
The HTML being used:
<div class="container">
<canvas id="examChart"></canvas>
</div>
I just have no idea, although I imagine this is a rather simple problem, any help would be greatly appreciated.
回答1:
You have to move your data within a dataset. If you take a look at the usage manual, a datasets array is used. The "hint" for datasets within the docs for time is also not that obvious (See headline).
See the snippet below:
I just copied the basic usage example and inserted the data from your first attempt (+ added few labels)
UPDATE 18.03.2020
I've updated the snippet to use Chart.js 2.8.0 and added following code, as suggested in the comment by @Erik
options: {
scales: {
xAxes: [{
type: 'time'
}]
}
}
var ctx = document.getElementById("examChart").getContext("2d");
var myChart = new Chart(ctx, {
type: 'line',
data: {
labels: [new Date("2015-3-15 13:3").toLocaleString(), new Date("2015-3-25 13:2").toLocaleString(), new Date("2015-4-25 14:12").toLocaleString()],
datasets: [{
label: 'Demo',
data: [{
t: new Date("2015-3-15 13:3"),
y: 12
},
{
t: new Date("2015-3-25 13:2"),
y: 21
},
{
t: new Date("2015-4-25 14:12"),
y: 32
}
],
backgroundColor: [
'rgba(255, 99, 132, 0.2)',
'rgba(54, 162, 235, 0.2)',
'rgba(255, 206, 86, 0.2)',
'rgba(75, 192, 192, 0.2)',
'rgba(153, 102, 255, 0.2)',
'rgba(255, 159, 64, 0.2)'
],
borderColor: [
'rgba(255,99,132,1)',
'rgba(54, 162, 235, 1)',
'rgba(255, 206, 86, 1)',
'rgba(75, 192, 192, 1)',
'rgba(153, 102, 255, 1)',
'rgba(255, 159, 64, 1)'
],
borderWidth: 1
}]
},
options: {
scales: {
xAxes: [{
type: 'time'
}]
}
}
});<script src="https://cdnjs.cloudflare.com/ajax/libs/Chart.js/2.8.0/Chart.bundle.js"></script>
<div class="container">
<canvas id="examChart"></canvas>
</div>回答2:
Building on what @RamizWachtler has answered, you can add to the options section of the chart to scale the times out properly. I'll note that this doesn't seem to work with Charts.js 2.3. Added a working snippet that uses the latest Charts.js version as of April 2019.
Additionally I've changed the time formatting to be ISO8601 compliant.
var chart = new Chart(ctx, {
type: 'line',
data: data,
options: {
scales: {
xAxes: [{
type: 'time',
distribution: 'linear'
}]
}
}
});
Source - https://www.chartjs.org/docs/latest/axes/cartesian/time.html
var ctx = document.getElementById("examChart").getContext("2d");
var myChart = new Chart(ctx, {
type: 'line',
data: {
labels: ["2015-03-15T13:03:00Z", "2015-03-25T13:02:00Z", "2015-04-25T14:12:00Z"],
datasets: [{
label: 'Demo',
data: [{
t: "2015-03-15T13:03:00Z",
y: 12
},
{
t: "2015-03-25T13:02:00Z",
y: 21
},
{
t: "2015-04-25T14:12:00Z",
y: 32
}
],
backgroundColor: [
'rgba(255, 99, 132, 0.2)',
'rgba(54, 162, 235, 0.2)',
'rgba(255, 206, 86, 0.2)',
'rgba(75, 192, 192, 0.2)',
'rgba(153, 102, 255, 0.2)',
'rgba(255, 159, 64, 0.2)'
],
borderColor: [
'rgba(255,99,132,1)',
'rgba(54, 162, 235, 1)',
'rgba(255, 206, 86, 1)',
'rgba(75, 192, 192, 1)',
'rgba(153, 102, 255, 1)',
'rgba(255, 159, 64, 1)'
],
borderWidth: 1
}]
},
options: {
scales: {
xAxes: [{
type: 'time',
distribution: 'linear'
}]
}
}
});<script src="https://cdnjs.cloudflare.com/ajax/libs/Chart.js/2.8.0-rc.1/Chart.bundle.js"></script>
<div class="container">
<canvas id="examChart"></canvas>
</div>回答3:
when using time, you have to use UTC time, as your local time is added(australia +10 hours / 36000 secs) so every country has a different time zone. the key is to use moment.utc in any conversion of time 0 seconds = moment.utc('1970-01-01 00:00:00')
use moment.utc('1970-01-01').add(3600, 'seconds')to add a value and then
from y-axis values or tool tip items, you have to reference
callback: value => {
date = moment.utc(value);
if(date.diff(moment.utc('1970-01-01 23:59:59'), 'minutes') === 0)
{
return null;
};
date.format('HH:mm:ss');
}
label: (item, data) => data.datasets[item.datasetIndex].label +" "+
moment.utc(data.datasets[item.datasetIndex].data[item.index]).format("HH:mm:ss")
https://lopeys.com/ironman/IMAUS_Charts_StackedTimes.htm
回答4:
My suggestion would be to add the moment.js library to your project and format your dates using moment. Also I'm not sure about using the "t" and "y" here. I'd add the time as labels and matched that with the x data:
var data = {
labels: [moment().format("YYYY-MM-DD"), moment().format("YYYY-MM-DD"), moment().format("YYYY-MM-DD")],
datasets: [
{
data: [12,21,32],
}
]
};
var myBarChart = Chart.Line(canvas,{
data:data,
});
There is a fiddle example here.
来源：https://stackoverflow.com/questions/47875045/chart-js-creating-a-line-graph-using-dates