[Chapter 15] 15.2 Reading Cookies
Author: David Flanagan
Date: Fri Aug 29 11:01:31 1997

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| Chapter 15 Saving State with Cookies |

## 15.2 Reading Cookies

When you use the `cookie` property in a JavaScript expression, the value it returns is a string containing all the cookies that apply to the current document. The string is a list of `name``=``value` pairs separated by semicolons, where `name` is the name of a cookie, and `value` is its string value. You can use the `String.indexOf()` and `String.substring()` methods to determine the value of the named cookie you are interested in. Or, you may find it easier to use `String.split()` to break the string into individual cookies.

Once you have obtained the value of a cookie in this way, you must interpret that value based on whatever format or encoding was used by the creator of that cookie. For example, the cookie might store multiple pieces of information in colon-separated fields. In this case, you would have to use appropriate string methods to extract the various fields of information.

The value of a cookie must not contain any semicolons, commas, or whitespace. Because these are commonly used characters, it is common to use the JavaScript `escape()` function to encode cookie values before storing them, and the `unescape()` function to decode the values after retrieving them.

Note that the `Document.cookie` property provides no way to obtain the domain, path, expiration, or secure fields associated with a cookie.

An Overview of Cookies |  | Storing Cookies