Read QueryString parameters in JavaScript

In this article I will explain with an example, how to read QueryString parameters in JavaScript.

There is no direct function or utility available to read QueryString parameter values in JavaScript.

This article will illustrate how to parse the URL of the page and then extract the QueryString parameter values using Plain JavaScript.

Redirecting with QueryString parameters using JavaScript

The following HTML Markup consists of an HTML TextBox, a DropDownList and a Button.

The Button has been assigned a JavaScript Click event handler which invokes the Send JavaScript function.

Inside the Send JavaScript function, the values of the TextBox and DropDownList are fetched and are encoded using the JavaScript encodeURIComponent function and added as QueryString parameters to a URL.

Finally, the page is redirected to the URL.

Name:

<br />

Technology:

</select>

function Send() {

var name = document.getElementById("txtName").value;

var tech = document.getElementById("ddlTechnolgy").value;

var url = "Page2.htm?name=" + encodeURIComponent(name) + "&technology=" + encodeURIComponent(tech);

window.location.href = url;

};

</script>

Reading QueryString parameters using JavaScript

The following HTML Markup consists of an HTML SPAN.

Inside the Window OnLoad event handler, the QueryString is extracted by splitting the URL of the current page using the Question mark (?) character.

Then a loop is executed and each QueryString parameter value is extracted by further splitting using the ampersand (&) character and the extracted values are decoded using the JavaScript decodeURIComponent function inserted as Key and Value pairs into an Array.

Finally, the QueryString parameter values are fetched from the Array using the name of the QueryString parameter i.e. the Key and displayed in HTML SPAN.