使用 Javascript 的会话 cookie

A simpler solution would be to use sessionStorage, in this case:

var myVariable = "Hello World";


sessionStorage['myvariable'] = myVariable;


var readValue = sessionStorage['myvariable'];
console.log(readValue);

However, keep in mind that sessionStorage saves everything as a string, so when working with arrays / objects, you can use JSON to store them:

var myVariable = {a:[1,2,3,4], b:"some text"};


sessionStorage['myvariable'] = JSON.stringify(myVariable);
var readValue = JSON.parse(sessionStorage['myvariable']);

A page session lasts for as long as the browser is open and survives over page reloads and restores. Opening a page in a new tab or window will cause a new session to be initiated.

So, when you close the page / tab, the data is lost.

Yes, that is correct.

Not putting an expires part in will create a session cookie, whether it is created in JavaScript or on the server.

See https://stackoverflow.com/a/532660/1901857

For the use case in the question (no server side code), sessionStorage is a simpler solution. But sessionStorage is client only, so would not work if you need to access the stored value on the server (e.g. user logins etc.)

For creating session only cookie with java script, you can use the following. This works for me.

document.cookie = "cookiename=value; expires=0; path=/";

then get cookie value as following

 //get cookie
var cookiename = getCookie("cookiename");
if (cookiename == "value") {
//write your script
}


//function getCookie
function getCookie(cname) {
var name = cname + "=";
var ca = document.cookie.split(';');
for (var i = 0; i < ca.length; i++) {
var c = ca[i];
while (c.charAt(0) == ' ') c = c.substring(1);
if (c.indexOf(name) != -1) return c.substring(name.length, c.length);
}
return "";
}

Okay to support IE we can leave "expires" completely and can use this

document.cookie = "mtracker=somevalue; path=/";

Use the below code for a setup session cookie, it will work until browser close. (make sure not close tab)

function setCookie(cname, cvalue, exdays) {
var d = new Date();
d.setTime(d.getTime() + (exdays*24*60*60*1000));
var expires = "expires="+ d.toUTCString();
document.cookie = cname + "=" + cvalue + ";" + expires + ";path=/";
}
function getCookie(cname) {
var name = cname + "=";
var decodedCookie = decodeURIComponent(document.cookie);
var ca = decodedCookie.split(';');
for(var i = 0; i <ca.length; i++) {
var c = ca[i];
while (c.charAt(0) == ' ') {
c = c.substring(1);
}
if (c.indexOf(name) == 0) {
return c.substring(name.length, c.length);
}
}
return false;
}
  

  

if(getCookie("KoiMilGaya")) {
//alert('found');
// Cookie found. Display any text like repeat user. // reload, other page visit, close tab and open again..
} else {
//alert('nothing');
// Display popup or anthing here. it shows on first visit only.
// this will load again when user closer browser and open again.
setCookie('KoiMilGaya','1');
}