Assigning JSON array retrived from local storage to JavaScript array

Question

I am storing an array of objects in localStorage, retriving it each time, attachibg the new object and again storing.

the code works fine, only if there is already an entry in localStorage Following is the code:

var companies=[];

companies=JSON.parse(localStorage.getItem("companies")); //IMP line

companies.push(company);
localStorage.setItem("companies", JSON.stringify(companies));

This works fine, when I comment the 'IMP line' for first time, so that a record is inserted with single record. once the local storage contains a record with key "companies" everything goes fine.

please suggest a condition that can be checked while inserting the array first time. Thank You.

tymeJV · Accepted Answer · 2015-01-13 14:28:41Z

5

You need to check:

var strCompanies = localStorage.getItem("companies")
var companies = strCompanies ? JSON.parse(strCompanies) : [];

answered Jan 13, 2015 at 14:28

tymeJV

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Comments

haim770 · Accepted Answer · 2015-01-13 14:29:29Z

1

localStorage.getItem will return null in case nothing found and so is JSON.parse(null). So you're ending up with companies being null.

Try this:

var companies=[];

if (localStorage.getItem("companies"))
    companies=JSON.parse(localStorage.getItem("companies")); //IMP line

companies.push(company);

localStorage.setItem("companies", JSON.stringify(companies));

See MDN

answered Jan 13, 2015 at 14:29

haim770

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1 Comment

SurajS Over a year ago

Thank you for explaination.. I was unaware that getItem returns null. now its simple:)

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