5 Ways to Pass Variables Between Pages In Javascript

Welcome to a tutorial on how to pass variables between pages in Javascript. Need to pass some data between different pages?

That’s all. But let us walk through more methods and examples in this guide, read on!

 

 

TLDR – QUICK SLIDES

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TABLE OF CONTENTS

 

 

 

METHOD 1) URL SEARCH PARAMETERS

<script>
function go () {
  // (A) VARIABLES TO PASS
  var one = "Foo Bar",
      two = ["Hello", "World"];

  // (B) URL PARAMETERS
  var params = new URLSearchParams();
  params.append("first", first);
  params.append("second", JSON.stringify(second));

  // (C) GO!
  var url = "1b-query.html?" + params.toString();
  location.href = url;
}
</script>
<input type="button" value="GO" onclick="go()">

<script>
function get () {
  // (A) GET THE PARAMETERS
  var params = new URLSearchParams(window.location.search),
      one = params.get("one"),
      two = JSON.parse(params.get("two"));

  // (B) IT WORKS!
  console.log(one);
  console.log(two);
}
</script>
<input type="button" value="GET" onclick="get()">

Some like to call it “URL search parameters”, “search query”, or maybe you have heard of “GET variables”. Simply put, we are just appending a string of ?KEY=VALUE data to the end of the URL. Yep, Javascript is fully capable of accessing the query string, and we can use that to pass data.

P.S. Take note that we cannot pass arrays and objects directly. We use JSON.stringify() to turn it into a string first, then JSON.parse() to turn it back into an array/object.

 

 

METHOD 2) SESSION STORAGE

<script>
function go () {
  // (A) VARIABLES TO PASS
  var one = "Foo Bar",
      two = ["Hello", "World"];
 
  // (B) SAVE TO SESSION STORAGE
  sessionStorage.setItem("one", one);
  sessionStorage.setItem("two", JSON.stringify(two));
 
  // (C) REDIRECT
  location.href = "2b-session-storage.html";
}
</script>
<input type="button" value="GO" onclick="go()">

<script>
function get () {
  // (A) GET FROM SESSION STORAGE
  var one = sessionStorage.getItem("one"),
      two = JSON.parse(sessionStorage.getItem("two"));

  // (B) IT WORKS!
  console.log(one);
  console.log(two);

  // (C) CLEAR SESSION STORAGE
  // sessionStorage.removeItem("KEY");
  // sessionStorage.clear();
}
</script>
<input type="button" value="GET" onclick="get()">

There is a temporary “sandbox data storage area” in Javascript called session storage. Very easy to use, only 4 functions to know:

• sessionStorage.setItem(KEY, VALUE)
• sessionStorage.getItem(KEY)
• sessionStorage.removeItem(KEY)
• sessionStorage.clear()

But please take note that the session storage will be automatically deleted once the user closes the tab/window.

P.S. Data will also not be passed when the user manually opens another tab/window for 2b-session-storage.html.

 

 

METHOD 3) LOCAL STORAGE

<script>
function go () {
  // (A) VARIABLES TO PASS
  var one = "Foo Bar",
      two = ["Hello", "World"];

  // (B) SAVE TO LOCAL STORAGE
  localStorage.setItem("one", one);
  localStorage.setItem("two", JSON.stringify(two));
 
  // (C) REDIRECT OR OPEN NEW WINDOW IF YOU WANT
  location.href = "3b-local-storage.html";
}
</script>
<input type="button" value="GO" onclick="go()">

<script>
function get () {
  // (A) GET FROM LOCAL STORAGE
  var first = localStorage.getItem("first"),
      second = JSON.parse(localStorage.getItem("second"));

  // (B) IT WORKS!
  console.log(one);
  console.log(two);

  // (C) CLEAR LOCAL STORAGE
  // localStorage.removeItem("KEY");
  // localStorage.clear();
}
</script>
<input type="button" value="GET" onclick="get()">

Looks familiar? That’s because local storage is the cousin of session storage. Yep, the same old temporary storage area, but local storage is persistent – Whatever is set in the local storage will stay until manually deleted. Yep, we can still retrieve data from the local storage even after the window is closed and reopened later.

 

METHOD 4) COOKIE

<script>
function store () {
  // (A) VARIABLES TO PASS
  var one = "Foo Bar",
      two = ["Hello", "World"];
 
  // (B) URL PARAMETERS + STORE INTO COOKIE
  // * WORKS, BUT NOT RECOMMENDED
  var params = new URLSearchParams();
  params.append("one", one);
  params.append("two", JSON.stringify(two));
  document.cookie = "pass=" + params.toString();
 
  // (C) REDIRECT
  location.href = "4b-cookie.html";
}
</script>
<input type="button" value="GO" onclick="go()">

<script>
function get () {
  // (A) GET BACK PASS VARS
  var passvars = document.cookie
    .split("; ")
    .find(row => row.startsWith("pass"))
    .substring(5);
 
  // (B) PARSE BACK
  var params = new URLSearchParams(passvars),
      one = params.get("one"),
      two = JSON.parse(params.get("two"));
 
  // (C) IT WORKS!
  console.log(one);
  console.log(two);
}
</script>
<input type="button" value="GET" onclick="get()">

You may have also heard of the cookie, a small token to keep some data… Anyway, just don’t mess with the cookie unless really necessary. Keep this one as a last desperate resort.

 

 

METHOD 5) NEW WINDOW

<script>
function go () {
  // (A) VARIABLES TO PASS
  var one = "Foo Bar",
      two = ["Hello", "World"];
 
  // (B) OPEN NEW WINDOW - JUST PASS VARIABLES TO NEW WINDOW
  var newwin = window.open("5b-window.html");
  newwin.onload = () => {
    newwin.one = one;
    newwin.two = two;
  };
}
</script>
<input type="button" value="GO" onclick="go()">

<script>
function get () {
  console.log(one);
  console.log(two);
}
</script>
<input type="button" value="GET" onclick="get()">

When we create var newwin = window.open(), we can “directly insert” the variables into the new window. As simple as that.

 

 

 

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EXAMPLE CODE DOWNLOAD

Click here for the source code on GitHub gist, just click on “download zip” or do a git clone. I have released it under the MIT license, so feel free to build on top of it or use it in your own project.

 

 

RECONSIDER YOUR PROCESSES!

The Stone Age of the Internet is long past. Instead of reloading and redirecting pages, we should be creating a “seamless experience” with modern technologies instead. For example, if you want to create a wizard form – Modern web development is more than capable of doing that. Check out the wizard form and Dynamic HTML links below.

 

LINKS & REFERENCES

• Window.sessionStorage – MDN
• Window.localStorage – MDN
• URL Search Params – MDN
• Document.cookie – MDN
• Simple Wizard Form – Code Boxx
• Beginner AJAX Tutorial – Code Boxx
• Dynamic HTML Content – Code Boxx

 

TUTORIAL VIDEO

 

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