get parameter value from cookie_问答_开发者_运维开发者技术经验分享

开发者 https://www.devze.com 2023-02-11 11:51 出处：网络

Hi I have a small problem. Currently I have 2 parameters saved in the browser cookie which ar开发者_StackOverflow中文版e ADV and LOC... Now I have a page with a form and the form got two hidden fields

相关专题：javascript

<input type="hidden" name="adv" value="" />
<input type="hidden" name="loc" value="" />

I need to get the values of adv and loc from the cookie and save them in the hidden form fields... How can i do this please? Thanks

document.cookie will get you all the cookies in the following format:

'adv=adv_val; loc=loc_val;'

To get a value from a cookie, you can use this function (from quirksmode):

function readCookie(name) {
    var nameEQ = name + "=";
    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,c.length);
        if (c.indexOf(nameEQ) == 0) return c.substring(nameEQ.length,c.length);
    }
    return null;
}

To fill in the hidden fields, you can loop though all the hidden fields, and get their respective cookies:

function hiddenCookies(){
  var inputs = document.getElementsByTagName('input');
  for(var i = 0; i < inputs.length; i++){
      var element = inputs[i];
      if(element.getAttribute('type') == 'hidden'){
          element.value = readCookie(element.name);
      }
  }
}

And then modify <body> to have an onload.

<body onload="hiddenCookies()">

Or with jQuery:

$(function(){
  $('input:hidden').each(function(i,v){
      v.value = readCookie(v.name);
  });
});

You can use this snippet to convert the cookie string into a map.

let cookieMap = document.cookie.split(";").map((str)=>str.split("=")).reduce(reduceToMap(map,curr),{});

function reduceToMap(map,currentArray) {
  // convert array to map
  map[currArray[0]] = currentArray[1];
  return map;
}

What this is doing is essentially the following:

Splitting the string into an array of strings (of the form "key=value")
Mapping each string of this array to an array of the form ["key","value"]
Reducing this array of arrays (of the form [ ["k1","v1"], ["k2","v2"] ]) into a map

Now you can simply access any cookie by doing the following:

let cookieName = "name of the cookie you want to access";
let cookieValue = cookieMap[cookieName];

get parameter value from cookie

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