Angular 6: saving data to local storage

问题:

I have a data table which display data from external API, I want the number of items /element on the table page should be saved in local storage

Here is what I have tried so far:

 ngOnInit() {
  this.moviesService.getPopularTVShows().subscribe(res => {
    this.dataSource = new MatTableDataSource(res.results);
    this.dataSource.paginator = this.paginator;
    this.dataSource.sort = this.sort;
    localStorage.setItem(this.dataSource, this.dataSource.length);
    console.log(localStorage.length);
  });
}

When I run my app, the console displays undefined

What is wrong with my code? any help or suggestion is welcomed, newbie trying new stuff.

回答1:

You should define a key name while storing data to local storage which should be a string and value should be a string

 localStorage.setItem('dataSource', this.dataSource.length);

and to print, you should use getItem

console.log(localStorage.getItem('dataSource'));

回答2:

First you should understand how localStorage works. you are doing wrong way to set/get values in local storage. Please read this for more information : How to Use Local Storage with JavaScript