String parsing in JavaScript / jQuery

Question

I have a string like url params. I want to get insurance value if insurance param comes only one time in string.

For example:

1. Following string should produce result: false

?LastName=abc&FirstName=xyz&insurance=2&insurance=3&insurance=4&insurance=5&BirthDate=01-01-2000

2. Following string should produce result: 2 (because only one insurance)

?LastName=abc&FirstName=xyz&insurance=2&BirthDate=01-01-2000

How can I do this in JavaScript / jQuery

I appreciate every answer. Thanks

you looking for [this](http://stackoverflow.com/questions/901115/get-querystring-values-with-jquery)? — indiPy, Mar 05 '11 at 10:38
@alliswell: Thanks. I used the top answer's function of question that you mentioned. It returns first **insurance** value without condsidering no. of **insurance** in string. I want to return **insurance** value only when there is only one **insurance** in the string. So now I have to add a check for the no of insurance in string. — Awan, Mar 05 '11 at 10:53
you are welcome, and use regex as it mentioned or simple conditional check will work. — indiPy, Mar 05 '11 at 11:00
See also the [Query String Object](http://plugins.jquery.com/project/query-object) plugin. — outis, Mar 05 '11 at 11:46

score 4 · Accepted Answer · answered Mar 05 '11 at 10:57

Here's a function that will do what you want

function checkInsurance( queryString ) {
    // a regular exression to find your result
    var rxp = /insurance=(\d+)/gi
    if( !queryString.match( rxp ) || queryString.match( rxp ).length !== 1 ) {
        // if there are no matches or more than one match return false
        return false;
    }
    // return the required number
    return rxp.exec( queryString )[1];
}

score 1 · Answer 2 · answered Mar 05 '11 at 11:15

+1 for @meouw - neat solution!

An alternative would be to use string.split. The following implementation is flexible about the param you are searching for and its value (i.e. any string).

function getUniqueParam (query, paramName) {
    var i, row, result = {};

    query = query.substring(1);
    //split query into key=values
    query = query.split('&');


    for (i = 0; i < query.length; i++) {
        row = query[i].split('=');

        // if duplicate then set value to false;
        if(result[row[0]]) {
            result[row[0]] = false;
        }
        else {
            result[row[0]] = row[1];
        }

    };

    // return the requested param value
    return result[paramName];
}


// Testing:

var a = '?LastName=abc&FirstName=xyz&insurance=2&insurance=3&insurance=4&insurance=5&BirthDate=01-01-2000';
var b = '?LastName=abc&FirstName=xyz&insurance=2&BirthDate=01-01-2000';

console.log(getUniqueParam(a, 'insurance'));
console.log(getUniqueParam(b, 'insurance'));

There is a discussion on regex vs. string.split performance [here](http://stackoverflow.com/questions/966697/performance-question-string-split-and-then-walk-on-the-array-or-regexp) — johnhunter, Mar 05 '11 at 11:17

String parsing in JavaScript / jQuery

2 Answers2