SyntaxError：尝试存储在本地存储中时，Angular2中位置0处JSON中的意外令牌u

Question

I have a json response like this.

   {
  "response": {
    "data": {
      "name": "ABC",
      "Id": "1234",
      "address": "adthhyrr"    
    }
  }
}

In service.ts I am doing a request like this to get the response data.

 public getResponseData() : Promise<any> {
      if(typeof(this.login_data) === "undefined") {
            return this.http.get('assets/response.json')
            .toPromise().then(res => {
                                  this.login_data = res.json().response.data;

                                  return this.login_data;
                }).catch(this.handleError);
      } else {
          return Promise.resolve(this.login_data);
      }
}

And I am storing the login_data in localstorage like this

  getAllData() {  
    if (localStorage.getItem('login_data') === null || localStorage.getItem('login_data') === undefined) {  
      localStorage.setItem('login_data', JSON.stringify(this.login_data)); 
      return this.login_data;  
    }  
    else {  
      var login_data = JSON.parse(localStorage.getItem('login_data'));  
      return login_data;  
    }  

  } 

And in component.ts class I am getting data like this

   this.logindata = this.myservice.getAllData();

But while doing this I am getting this error. SyntaxError: Unexpected token u in JSON at position 0 .

But if i am not storing in localstorage then i am doing like this in service.

public getAllData(): any {

return this.login_data;

}

And in component.ts file i am getting data by calling this method.

 this.logindata = this.myservice.getAllData();

And here it is working fine.But when i am trying to store data into localstorage and want to fetch from local storage i am getting this error. SyntaxError: Unexpected token u in JSON at position 0

Can anyone please tell me where exactly i am doing wrong.

Answer 1

The error SyntaxError: Unexpected token u in JSON at position 0 says that you are trying to parse an object to object which is not possible .

So, while retrieving from localStorage check the type and parse if it is not an object

Also change the if condition to, if ( !(localStorage.getItem('login_data'))) {

 getAllData() {
    var data = localStorage.getItem('login_data');
  if (!data) {
    localStorage.setItem('login_data', JSON.stringify(this.login_data));
    return this.login_data;
  } else {
      var login_data;
      if(typeof data == 'object')
        {
            login_data = data;
        }else{
            login_data = JSON.parse(data);


        }
        return login_data;
  }
}