import { Component } from '@angular/core' ; export interface PeriodicElement { name : string ; position : number ; weight : number ; symbol : string ; } const ELEMENT_DATA = [ { position : 1 , name : 'Hydrogen' , weight : 1.0079 , symbol : 'H' } , { position : 2 , name : 'Helium' , weight : 4.0026 , symbol : 'He' } , { position : 3 , name : 'Lithium' , weight : 6.941 , symbol : 'Li' } , { position : 4 , name : 'Beryllium' , weight : 9.0122 , symbol : 'Be' } , { position : 5 , name : 'Boron' , weight : 10.811 , symbol : 'B' } , { position : 6 , name : 'Carbon' , weight : 12.0107 , symbol : 'C' } , { position : 7 , name : 'Nitrogen' , weight : 14.0067 , symbol : 'N' } , { position : 8 , name : 'Oxygen' , weight : 15.9994 , symbol : 'O' } , { position : 9 , name : 'Fluorine' , weight : 18.9984 , symbol : 'F' } , { position : 10 , name : 'Neon' , weight : 20.1797 , symbol : 'Ne' } , ] ; title @ Component ( { selector : 'table-dynamic-columns-example' , styleUrls : [ 'table-dynamic-columns-example.css' ] , templateUrl : 'table-dynamic-columns-example.html' , } ) export class TableDynamicColumnsExample { displayedColumns : string [ ] = [ 'name' , 'weight' , 'symbol' , 'position' ] ; columnsToDisplay : string [ ] = this . displayedColumns . slice ( ) ; data : PeriodicElement [ ] = ELEMENT_DATA ; addColumn ( ) { const randomColumn = Math . floor ( Math . random ( ) * this . displayedColumns . length ) ; this . columnsToDisplay . push ( this . displayedColumns [ randomColumn ] ) ; } removeColumn ( ) { if ( this . columnsToDisplay . length ) { this . columnsToDisplay . pop ( ) ; } } shuffle ( ) { let currentIndex = this . columnsToDisplay . length ; while ( 0 !== currentIndex ) { let randomIndex = Math . floor ( Math . random ( ) * currentIndex ) ; currentIndex -= 1 ; let temp = this . columnsToDisplay [ currentIndex ] ; this . columnsToDisplay [ currentIndex ] = this . columnsToDisplay [ randomIndex ] ; this . columnsToDisplay [ randomIndex ] = temp ; } } }