如何从localStorage检索多个键和值

Question

I am storing multiple arrays to localstorage.

firstArray = [];
secArray = [];

var firsteobj = {class: class, subject: subject, school: school, area: area, zipcode: zipcode};  
firstArray.push(firstobj);
localStorage.firstRecord = JSON.stringify(firstArray);

var secobj = {student: student, grade: grade, age: age};     
secArray.push(secobj);
localStorage.secondRecord = JSON.stringify(secArray);

And I am retrieving from the localstorage through the function and download the file.

function DownloadRec() {
  var a = {};
  for (var i = 0; i < localStorage.length; i++) {
    var k = localStorage.key(i);
    var v = localStorage.getItem(k);
    a[k] = v;
    //alert(a[k]);
  }

  let dataUrl = 'data:application/json,' + encodeURIComponent(a[k]);
  let exportFileDefaultName = 'test.json';

  let linkElement = document.createElement('a');
  linkElement.setAttribute('href', dataUrl);
  linkElement.setAttribute('download', exportFileDefaultName);
  linkElement.click();
}

I could see both key(firstRecord,secRocord) and corresponding values to it in the browser. I could retrieve only the first key which is localstorage.firstRecord.... I would like to retrieve second key and values which is localstorage.secondRecord also.

Could you please suggest me.

Answer 1

The proper way to set/get localStorage is like this:

const myValue = [{ thing: 'myValue' }]
const mySerializedValue = JSON.stringify(myValue)

localStorage.setItem('myKey', mySerializedValue)
localStorage.getItem('myKey')

Also, I noticed "class" being used as a variable name. Might want to rename because "class" is a keyword in many programming languages, including es6 javascript.

Answer 2

Just create an array of objects like this:

  arr=[
       obj1:'',
       .
       .
       .
       obj2:''
       ]

and save it in browser using localStorage.setItem('objName') now you can retrieve the whole array.I think this is the best approach in your case.

Answer 3

You can store multiple values in localstorage using following. Also you can store data in the form of JSON objects as demonstrated:

//Store Values:
localStorage.setItem('someValue','hello');
let user = {name: 'SomeName', email: 'someemail@gmail.com'};
localStorage.setItem('jsonValue',JSON.stringify(user));

//Retrieve the values from localstorage
let temp = localStorage.getItem('someValue'); //temp is hello
let tempJSONString = localStorage.getItem('jsonValue'); 
let tempJSON = JSON.parse(tempJSONString );
//tempJSON.name is SomeName