如何从javascript中的字符串中提取值？

Question

I need some help with extracting values from a cookie using javascript.

The string in a cookie looks something like this:

string = 'id=1||price=500||name=Item name||shipping=0||quantity=2++id=2||price=1500||name=Some other name||shipping=10||quantity=2'

By using string.split() and string.replace() and a some ugly looking code I've somehow managed to get the values i need (price, name, shipping, quantity). But the problem is that sometimes not all of the strings in the cookie are the same. Sometimes the sting in a cookie will look something like this :

   string = 'id=c1||color=red||size=XL||price=500||name=Item name||shipping=0||quantity=2++id=c1||price=500||name=Item name||shipping=0||quantity=2'

with some items having color and size as parameters and sometimes only one of those.

Is there some more efficient way to explain to my computer that i want the part of the string after 'price=' to be a variable named 'price' etc.

I hope I'm making sense I've tried to be as precise as I could.

Anyway, thank you for any help

EDIT: I just wanted to say thanks to all the great people of StackOverflow for such wonderfull ideas. Because of all of your great suggestions I'm going out to get drunk tonight. Thank you all :)

Answer 1

Let's write a parser!

function parse(input)
{
    function parseSingle(input)
    {
        var parts = input.split('||'),
            part,
            record = {};

        for (var i=0; i<parts.length; i++)
        {
            part = parts[i].split('=');
            record[part[0]] = part[1];
        }

        return record;
    }

    var parts = input.split('++'),
        records = [];

    for (var i=0; i<parts.length; i++)
    {
        records.push(parseSingle(parts[i]));
    }

    return records;
}

---

Usage:

var string = 'id=1||price=500||name=Item name||shipping=0||quantity=2++id=2||price=1500||name=Some other name||shipping=10||quantity=2';

var parsed = parse(string);
/* parsed is:
[{id: "1", price: "500", name: "Item name", shipping: "0", quantity: "2"},
 {id: "2", price: "1500", name: "Some other name",  shipping: "10", quantity: "2"}]
*/

Answer 2

You can achieve this using regular expressions. For example, the regex /price=([0-9]+)/ will match price=XXX where XXX is one or more numbers. As this part of the regex is surrounded by parenthesis it explicitly captures the numeric part for you.

 var string = 'id=1||price=500||name=Item name||shipping=0||quantity=2++id=2||price=1500||name=Some other name||shipping=10||quantity=2' var priceRegex = /price=([0-9]+)/ var match = string.match(priceRegex); console.log(match[1]); // writes 500 to the console log

Answer 3

Try that:

var string = 'id=1||price=500||name=Item name||shipping=0||quantity=2++id=2||price=1500||name=Some other name||shipping=10||quantity=2';
var obj = new Array();
var arr = string.split('||');
for(var x=0; x<arr.length;x++){
    var temp = arr[x].split('=');
    obj[temp[0]] = temp[1]
}

alert(obj['id']); // alert 1

Answer 4

First, split your string into two (or more) parts by ++ separator:

var strings = myString.split('++');

then for each of the strings you want an object, right? So you need to have an array and fill it like that:

var objects = [];

for (var i = 0; i < strings.length; ++i) {
    var properties = strings[i].split('||');
    var obj = {};
    for (var j = 0; j < properties.length; ++j) {
          var prop = properties[j].split('=');
          obj[prop[0]] = prop[1]; //here you add property to your object, no matter what its name is
    }
    objects.push(obj);
}

thus you have an array of all objects constructed from your string. Naturally, in real life I'd add some checks that strings indeed satisfy the format etc. But the idea is clear, I hope.

Answer 5

If you can replace the || with & , you could try to parse it as if it were a query string . A personal note - JSON-formatted data would've been easier to work with.

Answer 6

I would attach the data to a javascript object.

  var settingsObj = {};
  var components = thatString.split('||');

  for(var j = 0; j < components.length; j++)
  {
       var keyValue = components[j].split('=');

       settingsObj[keyValue[0]] = keyValue[1];
  }

  // Now the key value pairs have been set, you can simply request them

  var id = settingsObj.id; // 1 or c1
  var name = settingsObj.name; // Item Name, etc

Answer 7

You're already using .split() to break down the string by ||just take that a step further and split each of those sections by = and assign everything on the left the field and the right the value

Answer 8

This should get the first match in the string:

string.match(/price=(\d{1,})/)[1]

Note this will only match the first price= in the string, not the second one.

Answer 9

If you can use jQuery, it wraps working with cookies and lets you access them like:

Reading a cookie: var comments = $.cookie('comments');

Writing a cookie: $.cookie('comments', 'expanded');

This post by someone else has a decent example: http://www.vagrantradio.com/2009/10/getting-and-setting-cookies-with-jquery.html

If you can't use jQuery, you need to do standard string parsing like you currently are (perhaps regular expressions instead of the string splitting / replacing might trim down your code) or find some other javascript library that you can use.

Answer 10

If you like eye candies in your code you can use a regexp based "search and don't replace" trick by John Resig ( cached here ) :

var extract = function(string) {
    var o = {};

    string.replace(/(.*?)=(.*?)(?:\|\||$)/g, function(all, key, value) {
        o[key] = value;
    });

    return o;
};

Then

var objects = string.split('++'), 
    i = objects.length;

for (;i--;) {
    objects[i] = extract(objects[i]);
}

Answer 11

var str = 'id=c1||color=red||size=XL||price=500||name=Item name||shipping=0||quantity=2++id=c1||price=500||name=Item name||shipping=0||quantity=2'
var items = str.split("++");
for (var i=0; i<items.length; i++) {
    var data = items[i].split("||");
    for (var j=0; j<data.length; j++) {
        var stuff = data[j].split("=");
        var n = stuff[0]; 
        var v = stuff[1];
        eval("var "+n+"='"+v+"'");
    }
    alert(id);
}

EDIT: As per JamieC's suggestion, you can eliminate eval("var "+n+"='"+v+"'"); and replace it with the (somewhat) safer window[n] = v; -- but you still have the simple problem that this will overwrite existing variables, not to mention you can't tell if the variable color was set on this iteration or if this one skipped it and the last one set it. Creating an empty object before the loop and populating it inside the loop (like every other answer suggests) is a better approach in almost every way.

Answer 12

You could do something like this, where you eval the strings when you split them.

<html>
<head>
<script type="text/javascript">
var string = 'id=c1||color=red||size=XL||price=500||name=Item name||shipping=0||quantity=2++id=c1||price=500||name=Item name||shipping=0||quantity=2'


var mySplitResult = string.split("||");

for(i = 0; i < mySplitResult.length; i++){
    document.write("<br /> Element " + i + " = " + mySplitResult[i]); 
    var assignment = mySplitResult[i].split("=");

    eval(assignment[0] + "=" + "\""+assignment[1]+"\"");
}
document.write("Price : " + price);
</script>
</head>
<body>
</body>
</html>

Answer 13

JSON.parse('[{' + string.replace(/\+\+/g, '},{').replace(/(\w*)=([\w\s]*)/g, '"$1":"$2"').replace(/\|\|/g, ',') + '}]')

将字符串转换为 JSON 格式，然后解析它。