Crockford's .supplant with multiple level objects

Question

/** Supplant **/
String.prototype.supplant = function(o) {
    return this.replace (/{([^{}]*)}/g,
        function (a, b) {
            var r = o[b];
            return typeof r === 'string' || typeof r === 'number' ? r : a;
        }
    );
};

Crockford is no doubt a JavaScript Grand Wizard, but his prototype is lacking when it comes to multiple level objects.

I would like this function to cover multiple level object replacement such as '{post.detailed}' could anyone help me with a revised version of supplant?

Answer 1

That shouldn't be too difficult. Use this replace function instead:

function (a, b) {
    var r = o,
        parts = b.split(".");
    for (var i=0; r && i<parts.length; i++)
        r = r[parts[i]];
    return typeof r === 'string' || typeof r === 'number' ? r : a;
}

Answer 2

I personally hate it when people stuff their own rubbish on the native types in JavaScript. If I were to write it I would do the following... But why no love for boolean?

function supplant(str, data) {
    return str.replace(/{([^{}]*)}/g, function (a, b) {

        // Split the variable into its dot notation parts
        var p = b.split(/\./);

        // The c variable becomes our cursor that will traverse the object
        var c = data;

        // Loop over the steps in the dot notation path
        for(var i = 0; i < p.length; ++i) {

            // If the key doesn't exist in the object do not process
            // mirrors how the function worked for bad values
            if(c[p[i]] == null)
                return a;

            // Move the cursor up to the next step
            c = c[p[i]];
        }

        // If the data is a string or number return it otherwise do
        // not process, return the value it was, i.e. {x}
        return typeof c === 'string' || typeof c === 'number' ? c : a;
    });
};

It doesn't support arrays btw, you would need to do some additional stuff to support that.

Answer 3

@Bergi method w/ support to boolean:

function (a, b) {
    var r = o,
        parts = b.split(".");
    for (var i=0; r && i<parts.length; i++)
        r = r[parts[i]];
    return typeof r === 'string' || typeof r === 'number' || typeof r === 'boolean' ? r : a;
}

Original Crockford's Supplant method w/ support to boolean:

if (!String.prototype.supplant) {
    String.prototype.supplant = function (o) {
        return this.replace(/{([^{}]*)}/g,
            function (a, b) {
                var r = o[b];
                return typeof r === 'string' || typeof r === 'number' || typeof r === 'boolean' ? r : a;
            }
        );
    };
}

Best of luck!

https://gist.github.com/fsschmitt/b48db17397499282ff8c36d73a36a8af