ERROR TypeError: Cannot read property 'length' of undefined angular 4 (NOT DUPLICATE) -


i getting following error leaderboardcomponent.html:27 error typeerror: cannot read property 'length' of undefined

the error in html:

<div *ngif="leaderboardtabledata.length > 0">

in component have:

export class leaderboardcomponent implements oninit {     leaderboardtabledata: array<leaderboardmodel>;     constructor(private leaderboardservice: leaderboardservice) { }      ngoninit() {         this.subscribeleaderboarddatafromstore();     }      subscribeleaderboarddatafromstore() {         this.leaderboardservice.getleaderboard()             .skipwhile((data) => { return _.isempty(data) })             .subscribe((data) => {                 if (!_.isempty(data)) {                     this.leaderboardtabledata = [data];                 }             });     }

and service:

getleaderboard(): observable<leaderboardmodel> {         return this.httputil.get(this.appconstants.end_point_leaderboard)             .map(response => <leaderboardmodel>response.json());     }

when tried following:

hello 1 <div *ngif="leaderboardtabledata.length > 0"> hello 2 hello 1 printed , got error.

this error occur if leaderboardtabledata not defined. easiest way fix following:

<div *ngif="leaderboardtabledata?.length > 0">

note: can use ?. operator inside html templates, not in code itself.


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