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Charts

Load Data On Demand

In this demo, the chart loads data as you pan it. Once a data block is loaded, it stays in memory to reduce requests to the server.

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<template> <DxChart id="chart" ref="chart" :data-source="chartDataSource" title="Temperature in Toronto (2017)" > <DxZoomAndPan argument-axis="pan"/> <DxScrollBar :visible="true"/> <DxArgumentAxis v-model:visual-range="currentVisualRange" :whole-range="bounds" argument-type="datetime" visual-range-update-mode="keep" /> <DxValueAxis :allow-decimals="false" name="temperature" > <DxTitle text="Temperature, &deg;C"> <DxFont color="#ff950c"/> </DxTitle> <DxLabel> <DxFont color="#ff950c"/> </DxLabel> </DxValueAxis> <DxSeries color="#ff950c" type="rangearea" argument-field="date" range-value1-field="minTemp" range-value2-field="maxTemp" name="Temperature range" /> <DxAnimation :enabled="false"/> <DxLoadingIndicator background-color="none"> <DxFont :size="14"/> </DxLoadingIndicator> <DxLegend :visible="false"/> </DxChart> </template> <script> import DxChart, { DxZoomAndPan, DxScrollBar, DxArgumentAxis, DxSeries, DxValueAxis, DxTitle, DxLabel, DxFont, DxAnimation, DxLoadingIndicator, DxLegend, } from 'devextreme-vue/chart'; import DataSource from 'devextreme/data/data_source'; import 'whatwg-fetch'; let packetsLock = 0; const HALFDAY = 43200000; export default { components: { DxChart, DxZoomAndPan, DxScrollBar, DxArgumentAxis, DxSeries, DxValueAxis, DxTitle, DxLabel, DxFont, DxAnimation, DxLoadingIndicator, DxLegend, }, data() { return { visualRange: { startValue: new Date(2017, 3, 1), endValue: new Date(2017, 3, 15), }, chartDataSource: new DataSource({ store: [], sort: 'date', paginate: false, }), bounds: { startValue: new Date(2017, 0, 1), endValue: new Date(2017, 11, 31), }, }; }, computed: { currentVisualRange: { get() { return this.visualRange; }, set(newRange) { const stateStart = this.visualRange.startValue; const currentStart = newRange.startValue; if (stateStart.valueOf() !== currentStart.valueOf()) { this.visualRange = newRange; } this.onVisualRangeChanged(); }, }, }, methods: { onVisualRangeChanged() { const component = this.$refs.chart.instance; const items = component.getDataSource().items(); if (!items.length || items[0].date - this.visualRange.startValue >= HALFDAY || this.visualRange.endValue - items[items.length - 1].date >= HALFDAY) { this.uploadDataByVisualRange(this.visualRange, component); } }, uploadDataByVisualRange(visualRange, component) { const dataSource = component.getDataSource(); const storage = dataSource.items(); const ajaxArgs = { startVisible: this.getDateString(visualRange.startValue), endVisible: this.getDateString(visualRange.endValue), startBound: this.getDateString(storage.length ? storage[0].date : null), endBound: this.getDateString(storage.length ? storage[storage.length - 1].date : null), }; if (ajaxArgs.startVisible !== ajaxArgs.startBound && ajaxArgs.endVisible !== ajaxArgs.endBound && !packetsLock) { packetsLock += 1; component.showLoadingIndicator(); this.getDataFrame(ajaxArgs) .then((dataFrame) => { packetsLock -= 1; const componentStorage = dataSource.store(); dataFrame .map((i) => ({ date: new Date(i.Date), minTemp: i.MinTemp, maxTemp: i.MaxTemp, })) .forEach((item) => componentStorage.insert(item)); dataSource.reload(); this.onVisualRangeChanged(); }) .catch(() => { packetsLock -= 1; dataSource.reload(); }); } }, getDataFrame(args) { let params = '?'; params += `startVisible=${args.startVisible} &endVisible=${args.endVisible} &startBound=${args.startBound} &endBound=${args.endBound}`; return fetch(`https://js.devexpress.com/Demos/WidgetsGallery/data/temperatureData${params}`) .then((response) => response.json()); }, getDateString(dateTime) { return dateTime ? dateTime.toLocaleDateString('en-US') : ''; }, }, }; </script> <style> #chart { height: 440px; } </style>
import { createApp } from 'vue'; import App from './App.vue'; createApp(App).mount('#app');
<!DOCTYPE html> <html> <head> <title>DevExtreme Demo</title> <meta http-equiv="X-UA-Compatible" content="IE=edge" /> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1.0" /> <link rel="stylesheet" type="text/css" href="https://cdn3.devexpress.com/jslib/21.2.3/css/dx.common.css" /> <link rel="stylesheet" type="text/css" href="https://cdn3.devexpress.com/jslib/21.2.3/css/dx.light.css" /> <script src="https://unpkg.com/core-js@2.4.1/client/shim.min.js"></script> <script src="https://unpkg.com/systemjs@0.21.3/dist/system.js"></script> <script type="text/javascript" src="config.js"></script> <script type="text/javascript"> System.import("./index.js"); </script> </head> <body class="dx-viewport"> <div class="demo-container"> <div id="app"> </div> </div> </body> </html>
window.config = { transpiler: 'plugin-babel', meta: { '*.vue': { loader: 'vue-loader', }, 'devextreme/localization.js': { 'esModule': true, }, }, paths: { 'npm:': 'https://unpkg.com/', }, map: { 'vue': 'npm:vue@3.0.0/dist/vue.esm-browser.js', 'vue-loader': 'npm:dx-systemjs-vue-browser@1.0.15/index.js', 'whatwg-fetch': 'npm:whatwg-fetch@2.0.4/fetch.js', 'mitt': 'npm:mitt/dist/mitt.umd.js', 'rrule': 'npm:rrule@2.6.6/dist/es5/rrule.js', 'luxon': 'npm:luxon@1.28.0/build/global/luxon.min.js', 'es6-object-assign': 'npm:es6-object-assign@1.1.0', 'devextreme': 'npm:devextreme@21.2.3/cjs', 'devextreme-vue': 'npm:devextreme-vue@21.2.3', 'jszip': 'npm:jszip@3.7.1/dist/jszip.min.js', 'devextreme-quill': 'npm:devextreme-quill@1.5.5/dist/dx-quill.min.js', 'devexpress-diagram': 'npm:devexpress-diagram@2.1.37/dist/dx-diagram.js', 'devexpress-gantt': 'npm:devexpress-gantt@3.1.24/dist/dx-gantt.js', '@devextreme/vdom': 'npm:@devextreme/vdom@2.2.3', '@devextreme/runtime': 'npm:@devextreme/runtime@2.3.8', 'inferno': 'npm:inferno@7.4.10/dist/inferno.min.js', 'inferno-compat': 'npm:inferno-compat@7.4.10/dist/inferno-compat.min.js', 'inferno-create-element': 'npm:inferno-create-element@7.4.10/dist/inferno-create-element.min.js', 'inferno-dom': 'npm:inferno-dom@1.0.7/dist/inferno-dom.min.js', 'inferno-hydrate': 'npm:inferno-hydrate@7.4.10/dist/inferno-hydrate.min.js', 'inferno-clone-vnode': 'npm:inferno-clone-vnode@7.4.10/dist/inferno-clone-vnode.min.js', 'inferno-create-class': 'npm:inferno-create-class@7.4.10/dist/inferno-create-class.min.js', 'inferno-extras': 'npm:inferno-extras@7.4.10/dist/inferno-extras.min.js', 'plugin-babel': 'npm:systemjs-plugin-babel@0.0.25/plugin-babel.js', 'systemjs-babel-build': 'npm:systemjs-plugin-babel@0.0.25/systemjs-babel-browser.js', }, packages: { 'devextreme-vue': { main: 'index.js', }, 'devextreme': { defaultExtension: 'js', }, '@devextreme/vdom': { defaultExtension: 'js', }, 'devextreme/events/utils': { main: 'index', }, 'devextreme/events': { main: 'index', }, 'es6-object-assign': { main: './index.js', defaultExtension: 'js', }, }, packageConfigPaths: [ 'npm:@devextreme/*/package.json', 'npm:@devextreme/runtime@2.3.8/inferno/package.json', ], babelOptions: { sourceMaps: false, stage0: true, }, }; System.config(window.config);