Using Chart.js on Angular 4

Question

I'm trying to use Chart.js with Angular 4, I saw an example on the chart.js documents but it's using a < script > tag to pull the script so it doesn't work on the component. This is how I tried to fit into Angular:

TS

export class GraphicsComponent implements OnInit {    ctx = document.getElementById("myChart");   myChart = new Chart(this.ctx, {     type: 'pie',     data: {         labels: ["New", "In Progress", "On Hold"],         datasets: [{             label: '# of Votes',             data: [1,2,3],             backgroundColor: [                 'rgba(255, 99, 132, 1)',                 'rgba(54, 162, 235, 1)',                 'rgba(255, 206, 86, 1)'             ],             borderWidth: 1         }]     },     options: {       responsive: false,       display:true     }   });    constructor() { }    ngOnInit() {   }  } 

HTML

<canvas id="myChart" width="700" height="400"></canvas> 

Any idea how I would make it work?

EDIT: I have updated my code with the import and I'm now receiving an error.

Import Code:

import * as Chart from 'chart.js' 

Error on chrome console:

ERROR Error: Uncaught (in promise): TypeError: Cannot read property 'length' of null TypeError: Cannot read property 'length' of null     at Object.acquireContext (platform.dom.js:333)     at Chart.construct (core.controller.js:74)     at new Chart (core.js:42)     at new GraphicsComponent (graphics.component.ts:12)     at createClass (core.es5.js:10922)     at createDirectiveInstance (core.es5.js:10756)     at createViewNodes (core.es5.js:12197)     at createRootView (core.es5.js:12092)     at callWithDebugContext (core.es5.js:13475)     at Object.debugCreateRootView [as createRootView] (core.es5.js:12792)     at Object.acquireContext (platform.dom.js:333)     at Chart.construct (core.controller.js:74)     at new Chart (core.js:42)     at new GraphicsComponent (graphics.component.ts:12)     at createClass (core.es5.js:10922)     at createDirectiveInstance (core.es5.js:10756)     at createViewNodes (core.es5.js:12197)     at createRootView (core.es5.js:12092)     at callWithDebugContext (core.es5.js:13475)     at Object.debugCreateRootView [as createRootView] (core.es5.js:12792)     at resolvePromise (zone.js:795)     at resolvePromise (zone.js:766)     at zone.js:844     at ZoneDelegate.webpackJsonp.../../../../zone.js/dist/zone.js.ZoneDelegate.invokeTask (zone.js:425)     at Object.onInvokeTask (core.es5.js:3881)     at ZoneDelegate.webpackJsonp.../../../../zone.js/dist/zone.js.ZoneDelegate.invokeTask (zone.js:424)     at Zone.webpackJsonp.../../../../zone.js/dist/zone.js.Zone.runTask (zone.js:192)     at drainMicroTaskQueue (zone.js:602)     at <anonymous> 

Answer 1

In my Angular 6.1 site, I am using chart.js by itself in mgechev/angular-seed.

As of writing this response, Chart.js developers have some work to do to make exporting its members compliant with newer standards so rollups may be problematic.

To get Chart.js 2.7.x to work after installing package chart.js and types @types/chart.js in this angular-seed, all I needed to do is:

1. Update project.config.ts to include ROLLUP_NAMED_EXPORTS to get rollup to work properly (if you're using a rollup).

   this.ROLLUP_NAMED_EXPORTS = [   ...this.ROLLUP_NAMED_EXPORTS,   { 'node_modules/chart.js/src/chart.js': ['Chart'] } ]; 

2. Update project.config.ts to include additional packages. This seed uses SystemJS config. This might vary if you're using something else.

   // Add packages const additionalPackages: ExtendPackages[] = [  { name: 'chart.js', path: 'node_modules/chart.js/dist/Chart.bundle.min.js' },    ...  ]; 

3. In your component

   import { Chart } from 'chart.js';  ...  export class MyComponent implements OnInit {  @ViewChild('myChart') myChartRef: ElementRef; chartObj: Chart;  ... } 

   Then load chart configuration in ngOnInit() per Chart.js documentation

4. HTML will look something like this:

   <div class="chart-container">    <canvas #myChart></canvas> </div> 

Answer 2

You can install the package, along with the types for full functionality in a typescript environment such as Angular:

npm install --save chart.js && npm install --save-dev @types/chart.js

Then in your component you can now import * as Chart from 'chart.js' and use it in your typescript environment. Check out this example for implementation methods using typescript.

Because you need to get the canvas from the DOM you need to make sure it's rendered before attempting to access it. This can be accomplished with AfterViewInit.

import { Component, AfterViewInit } from '@angular/core'; import * as Chart from 'chart.js'  export class MyChartComponent implements AfterViewInit {    canvas: any;   ctx: any;    ngAfterViewInit() {     this.canvas = document.getElementById('myChart');     this.ctx = this.canvas.getContext('2d');     let myChart = new Chart(this.ctx, {       type: 'pie',       data: {           labels: ["New", "In Progress", "On Hold"],           datasets: [{               label: '# of Votes',               data: [1,2,3],               backgroundColor: [                   'rgba(255, 99, 132, 1)',                   'rgba(54, 162, 235, 1)',                   'rgba(255, 206, 86, 1)'               ],               borderWidth: 1           }]       },       options: {}     });   }  }