Virtualization (Vue)

The FlexGrid control allows you to implement a simple type of 'infinite scrolling' through the use of the viewRange property. When the user scrolls to the bottom of the grid, the code adds items to the grid's itemsSource. If you inspect the DOM, you will notice that no matter how large the itemsSource gets, the number of DOM elements remains constant. The data is 'virtualized'.

Learn about FlexGrid | FlexGrid API Reference

This example uses Vue.

<template> <div class="container-fluid"> <wj-flex-grid :initialized="initializeGrid" :itemsSource="data"> </wj-flex-grid> <p> The grid now has <span id='rowCount'>{{ rowCount }}</span> rows and <span id='cellCount'>{{ cellCount }}</span> cell elements. </p> </div> </template> <script> import "@mescius/wijmo.styles/wijmo.css"; import "bootstrap.css"; import { createApp } from "vue" import * as wjcGrid from '@mescius/wijmo.grid'; import { registerGrid } from '@mescius/wijmo.vue2.grid'; import { registerInput } from '@mescius/wijmo.vue2.input'; import { getData } from './data'; let App = { name: "App", data: function () { return { data: getData(100), rowCount: 0, cellCount: 0 } }, methods: { initializeGrid(flex) { this.rowCount = flex.rows.length; this.cellCount = flex.hostElement.querySelectorAll('.wj-cell').length; flex.updatedView.addHandler((s) => { this.rowCount = s.rows.length; this.cellCount = s.hostElement.querySelectorAll('.wj-cell').length; }); flex.scrollPositionChanged.addHandler((s) => { // if we're close to the bottom, add 20 items if (s.viewRange.bottomRow >= s.rows.length - 1) { let view = s.collectionView; let index = view.currentPosition; // keep position in case the view is sorted this._addData(this.data, 20); view.refresh(); view.currentPosition = index; } }); }, _addData(data, cnt) { let more = getData(cnt, data.length); for (let i = 0; i < more.length; i++) { data.push(more[i]) } } } }; const app = createApp(App); // register all components and directives from Wijmo modules registerGrid(app) registerInput(app) app.mount('#app'); </script> <style> .wj-flexgrid { height: 250px; } #rowCount, #cellCount { font-weight: bold; } body { margin-bottom: 24pt; } </style>
<!DOCTYPE html> <html lang="en"> <head> <meta charset="utf-8"> <meta http-equiv="X-UA-Compatible" content="IE=edge"> <title>MESCIUS Wijmo FlexGrid Scroll Virtualization</title> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <!-- SystemJS --> <script src="https://cdnjs.cloudflare.com/ajax/libs/systemjs/0.21.5/system.src.js" integrity="sha512-skZbMyvYdNoZfLmiGn5ii6KmklM82rYX2uWctBhzaXPxJgiv4XBwJnFGr5k8s+6tE1pcR1nuTKghozJHyzMcoA==" crossorigin="anonymous"></script> <script src="systemjs.config.js"></script> <script> System.import('./src/app.vue'); </script> </head> <body> <div id="app"> </div> </body> </html>
export function getData(cnt, start) { let data = []; let countries = 'USA,Germany,UK,Japan,Italy,Greece'.split(','); if (!start) start = 0; for (let i = 0; i < cnt; i++) { data.push({ id: i + start, country: countries[i % countries.length], date: new Date(2014, i % 12, i % 28), amount: Math.random() * 10000, active: i % 4 === 0 }); } return data; }
(function (global) { System.config({ transpiler: 'plugin-babel', babelOptions: { es2015: true }, meta: { '*.css': { loader: 'css' }, '*.vue': { loader: 'vue-loader' } //'*.vue': { loader: 'systemjs-plugin-vue' } }, paths: { // paths serve as alias 'npm:': 'node_modules/' }, // map tells the System loader where to look for things map: { '@mescius/wijmo': 'npm:@mescius/wijmo/index.js', '@mescius/wijmo.input': 'npm:@mescius/wijmo.input/index.js', '@mescius/wijmo.styles': 'npm:@mescius/wijmo.styles', '@mescius/wijmo.cultures': 'npm:@mescius/wijmo.cultures', '@mescius/wijmo.chart': 'npm:@mescius/wijmo.chart/index.js', '@mescius/wijmo.chart.analytics': 'npm:@mescius/wijmo.chart.analytics/index.js', '@mescius/wijmo.chart.animation': 'npm:@mescius/wijmo.chart.animation/index.js', '@mescius/wijmo.chart.annotation': 'npm:@mescius/wijmo.chart.annotation/index.js', '@mescius/wijmo.chart.finance': 'npm:@mescius/wijmo.chart.finance/index.js', '@mescius/wijmo.chart.finance.analytics': 'npm:@mescius/wijmo.chart.finance.analytics/index.js', '@mescius/wijmo.chart.hierarchical': 'npm:@mescius/wijmo.chart.hierarchical/index.js', '@mescius/wijmo.chart.interaction': 'npm:@mescius/wijmo.chart.interaction/index.js', '@mescius/wijmo.chart.radar': 'npm:@mescius/wijmo.chart.radar/index.js', '@mescius/wijmo.chart.render': 'npm:@mescius/wijmo.chart.render/index.js', '@mescius/wijmo.chart.webgl': 'npm:@mescius/wijmo.chart.webgl/index.js', '@mescius/wijmo.chart.map': 'npm:@mescius/wijmo.chart.map/index.js', '@mescius/wijmo.gauge': 'npm:@mescius/wijmo.gauge/index.js', '@mescius/wijmo.grid': 'npm:@mescius/wijmo.grid/index.js', '@mescius/wijmo.grid.detail': 'npm:@mescius/wijmo.grid.detail/index.js', '@mescius/wijmo.grid.filter': 'npm:@mescius/wijmo.grid.filter/index.js', '@mescius/wijmo.grid.search': 'npm:@mescius/wijmo.grid.search/index.js', '@mescius/wijmo.grid.grouppanel': 'npm:@mescius/wijmo.grid.grouppanel/index.js', '@mescius/wijmo.grid.multirow': 'npm:@mescius/wijmo.grid.multirow/index.js', '@mescius/wijmo.grid.transposed': 'npm:@mescius/wijmo.grid.transposed/index.js', '@mescius/wijmo.grid.transposedmultirow': 'npm:@mescius/wijmo.grid.transposedmultirow/index.js', '@mescius/wijmo.grid.pdf': 'npm:@mescius/wijmo.grid.pdf/index.js', '@mescius/wijmo.grid.sheet': 'npm:@mescius/wijmo.grid.sheet/index.js', '@mescius/wijmo.grid.xlsx': 'npm:@mescius/wijmo.grid.xlsx/index.js', '@mescius/wijmo.grid.selector': 'npm:@mescius/wijmo.grid.selector/index.js', '@mescius/wijmo.grid.cellmaker': 'npm:@mescius/wijmo.grid.cellmaker/index.js', '@mescius/wijmo.nav': 'npm:@mescius/wijmo.nav/index.js', '@mescius/wijmo.odata': 'npm:@mescius/wijmo.odata/index.js', '@mescius/wijmo.olap': 'npm:@mescius/wijmo.olap/index.js', '@mescius/wijmo.rest': 'npm:@mescius/wijmo.rest/index.js', '@mescius/wijmo.pdf': 'npm:@mescius/wijmo.pdf/index.js', '@mescius/wijmo.pdf.security': 'npm:@mescius/wijmo.pdf.security/index.js', '@mescius/wijmo.viewer': 'npm:@mescius/wijmo.viewer/index.js', '@mescius/wijmo.xlsx': 'npm:@mescius/wijmo.xlsx/index.js', '@mescius/wijmo.undo': 'npm:@mescius/wijmo.undo/index.js', '@mescius/wijmo.interop.grid': 'npm:@mescius/wijmo.interop.grid/index.js', '@mescius/wijmo.touch': 'npm:@mescius/wijmo.touch/index.js', '@mescius/wijmo.cloud': 'npm:@mescius/wijmo.cloud/index.js', '@mescius/wijmo.barcode': 'npm:@mescius/wijmo.barcode/index.js', '@mescius/wijmo.barcode.common': 'npm:@mescius/wijmo.barcode.common/index.js', '@mescius/wijmo.barcode.composite': 'npm:@mescius/wijmo.barcode.composite/index.js', '@mescius/wijmo.barcode.specialized': 'npm:@mescius/wijmo.barcode.specialized/index.js', "@mescius/wijmo.vue2.chart.analytics": "npm:@mescius/wijmo.vue2.chart.analytics/index.js", "@mescius/wijmo.vue2.chart.animation": "npm:@mescius/wijmo.vue2.chart.animation/index.js", "@mescius/wijmo.vue2.chart.annotation": "npm:@mescius/wijmo.vue2.chart.annotation/index.js", "@mescius/wijmo.vue2.chart.finance.analytics": "npm:@mescius/wijmo.vue2.chart.finance.analytics/index.js", "@mescius/wijmo.vue2.chart.finance": "npm:@mescius/wijmo.vue2.chart.finance/index.js", "@mescius/wijmo.vue2.chart.hierarchical": "npm:@mescius/wijmo.vue2.chart.hierarchical/index.js", "@mescius/wijmo.vue2.chart.interaction": "npm:@mescius/wijmo.vue2.chart.interaction/index.js", "@mescius/wijmo.vue2.chart.radar": "npm:@mescius/wijmo.vue2.chart.radar/index.js", '@mescius/wijmo.vue2.chart.map': 'npm:@mescius/wijmo.vue2.chart.map/index.js', "@mescius/wijmo.vue2.chart": "npm:@mescius/wijmo.vue2.chart/index.js", "@mescius/wijmo.vue2.core": "npm:@mescius/wijmo.vue2.core/index.js", "@mescius/wijmo.vue2.gauge": "npm:@mescius/wijmo.vue2.gauge/index.js", "@mescius/wijmo.vue2.grid.detail": "npm:@mescius/wijmo.vue2.grid.detail/index.js", "@mescius/wijmo.vue2.grid.filter": "npm:@mescius/wijmo.vue2.grid.filter/index.js", "@mescius/wijmo.vue2.grid.grouppanel": "npm:@mescius/wijmo.vue2.grid.grouppanel/index.js", '@mescius/wijmo.vue2.grid.search': 'npm:@mescius/wijmo.vue2.grid.search/index.js', "@mescius/wijmo.vue2.grid.multirow": "npm:@mescius/wijmo.vue2.grid.multirow/index.js", "@mescius/wijmo.vue2.grid.sheet": "npm:@mescius/wijmo.vue2.grid.sheet/index.js", '@mescius/wijmo.vue2.grid.transposed': 'npm:@mescius/wijmo.vue2.grid.transposed/index.js', '@mescius/wijmo.vue2.grid.transposedmultirow': 'npm:@mescius/wijmo.vue2.grid.transposedmultirow/index.js', "@mescius/wijmo.vue2.grid": "npm:@mescius/wijmo.vue2.grid/index.js", "@mescius/wijmo.vue2.input": "npm:@mescius/wijmo.vue2.input/index.js", "@mescius/wijmo.vue2.olap": "npm:@mescius/wijmo.vue2.olap/index.js", "@mescius/wijmo.vue2.viewer": "npm:@mescius/wijmo.vue2.viewer/index.js", "@mescius/wijmo.vue2.nav": "npm:@mescius/wijmo.vue2.nav/index.js", "@mescius/wijmo.vue2.base": "npm:@mescius/wijmo.vue2.base/index.js", '@mescius/wijmo.vue2.barcode.common': 'npm:@mescius/wijmo.vue2.barcode.common/index.js', '@mescius/wijmo.vue2.barcode.composite': 'npm:@mescius/wijmo.vue2.barcode.composite/index.js', '@mescius/wijmo.vue2.barcode.specialized': 'npm:@mescius/wijmo.vue2.barcode.specialized/index.js', 'bootstrap.css': 'npm:bootstrap/dist/css/bootstrap.min.css', 'jszip': 'npm:jszip/dist/jszip.js', 'css': 'npm:systemjs-plugin-css/css.js', 'vue': 'npm:vue/dist/vue.cjs.js', '@vue/compiler-dom':'npm:@vue/compiler-dom/dist/compiler-dom.global.prod.js', '@vue/runtime-dom':'npm:@vue/runtime-dom/dist/runtime-dom.global.prod.js', '@vue/shared':'npm:@vue/shared/dist/shared.cjs.js', '@vue/compiler-dom':'npm:@vue/compiler-dom/dist/compiler-dom.global.prod.js', '@vue/runtime-dom':'npm:@vue/runtime-dom/dist/runtime-dom.global.prod.js', '@vue/shared':'npm:@vue/shared/dist/shared.cjs.js', '@vue/compiler-dom':'npm:@vue/compiler-dom/dist/compiler-dom.global.prod.js', '@vue/runtime-dom':'npm:@vue/runtime-dom/dist/runtime-dom.global.prod.js', '@vue/shared':'npm:@vue/shared/dist/shared.cjs.js', '@vue/compiler-dom':'npm:@vue/compiler-dom/dist/compiler-dom.global.prod.js', '@vue/runtime-dom':'npm:@vue/runtime-dom/dist/runtime-dom.global.prod.js', '@vue/shared':'npm:@vue/shared/dist/shared.cjs.js', '@vue/compiler-dom':'npm:@vue/compiler-dom/dist/compiler-dom.global.prod.js', '@vue/runtime-dom':'npm:@vue/runtime-dom/dist/runtime-dom.global.prod.js', '@vue/shared':'npm:@vue/shared/dist/shared.cjs.js', '@vue/compiler-dom':'npm:@vue/compiler-dom/dist/compiler-dom.global.prod.js', '@vue/runtime-dom':'npm:@vue/runtime-dom/dist/runtime-dom.global.prod.js', '@vue/shared':'npm:@vue/shared/dist/shared.cjs.js', '@vue/compiler-dom':'npm:@vue/compiler-dom/dist/compiler-dom.global.prod.js', '@vue/runtime-dom':'npm:@vue/runtime-dom/dist/runtime-dom.global.prod.js', '@vue/shared':'npm:@vue/shared/dist/shared.cjs.js', '@vue/compiler-dom':'npm:@vue/compiler-dom/dist/compiler-dom.global.prod.js', '@vue/runtime-dom':'npm:@vue/runtime-dom/dist/runtime-dom.global.prod.js', '@vue/shared':'npm:@vue/shared/dist/shared.cjs.js', 'vue-loader': 'npm:systemjs-vue-browser/index.js', //'systemjs-plugin-vue': 'npm:systemjs-plugin-vue/index.js', 'plugin-babel': 'npm:systemjs-plugin-babel/plugin-babel.js', 'systemjs-babel-build': 'npm:systemjs-plugin-babel/systemjs-babel-browser.js' }, // packages tells the System loader how to load when no filename and/or no extension packages: { src: { defaultExtension: 'js' }, rxjs: { defaultExtension: 'js' }, "node_modules": { defaultExtension: 'js' }, wijmo: { defaultExtension: 'js', } } }); })(this);