Get cookie by name

cookies, javascript

Solution

One approach, which avoids iterating over an array, would be:

function getCookie(name) {
  const value = `; ${document.cookie}`;
  const parts = value.split(`; ${name}=`);
  if (parts.length === 2) return parts.pop().split(';').shift();
}

Walkthrough

Splitting a string by token will produce either, an array with one string (same value), in case token does not exist in a string, or an array with two strings , in case token is found in a string .

The first (left) element is string of what was before the token, and the second one (right) is what is string of what was after the token.

(NOTE: in case string starts with a token, first element is an empty string)

Considering that cookies are stored as follows:

"{name}={value}; {name}={value}; ..."

in order to retrieve specific cookie value, we just need to get string that is after "; {name}=" and before next ";". Before we do any processing, we prepend the cookies string with "; ", so that every cookie name, including the first one, is enclosed with "; " and "=":

"; {name}={value}; {name}={value}; ..."

Now, we can first split by "; {name}=", and if token is found in a cookie string (i.e. we have two elements), we will end up with second element being a string that begins with our cookie value. Then we pull that out from an array (i.e. pop), and repeat the same process, but now with ";" as a token, but this time pulling out the left string (i.e. shift) to get the actual token value.

Problem

I have a getter to get the value from a cookie. Now I have 2 cookies by the name `shares=` and by the name `obligations=` . I want to make this getter only to get the values from the obligations cookie. How do I do this? So the `for` splits the data into separate values and puts it in an array. ``` function getCookie1() { // What do I have to add here to look only in the "obligations=" cookie? // Because now it searches all the cookies. var elements = document.cookie.split('='); var obligations= elements[1].split('%'); for (var i = 0; i < obligations.length - 1; i++) { var tmp = obligations[i].split('$'); addProduct1(tmp[0], tmp[1], tmp[2], tmp[3]); } } ```

Original source

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