Get url parameter jquery Or How to Get Query String Values In js

Admittedly I'm adding my answer to an over-answered question, but this has the advantages of:

-- Not depending on any outside libraries, including jQuery

-- Not polluting global function namespace, by extending 'String'

-- Not creating any global data and doing unnecessary processing after match found

-- Handling encoding issues, and accepting (assuming) non-encoded parameter name

-- Avoiding explicit for loops

String.prototype.urlParamValue = function() {
    var desiredVal = null;
    var paramName = this.valueOf();
    window.location.search.substring(1).split('&').some(function(currentValue, _, _) {
        var nameVal = currentValue.split('=');
        if ( decodeURIComponent(nameVal[0]) === paramName ) {
            desiredVal = decodeURIComponent(nameVal[1]);
            return true;
        }
        return false;
    });
    return desiredVal;
};

Then you'd use it as:

var paramVal = "paramName".urlParamValue() // null if no match