Format providers

Separated by a : an argument can contain a format expression at the right side.

So you can define custom logic to convert an argument value.

Lets say we want to define a format provider that converts values to upper and lower case strings:

JavaScript

StringFormat.addFormatProvider(function(ctx) {    
    var toStringSafe = function() { 
        return ctx.value ? ctx.value.toString() : "";
    }

    if (ctx.expression === "upper") {
        // UPPER case
        ctx.handled = true;
        return toStringSafe().toUpperCase();
    }

    if (ctx.expression === "lower") {
        // LOWER case
        ctx.handled = true;
        return toStringSafe().toLowerCase();
    }
});

Now you can use the extended logic in your code:

JavaScript

// MARCEL kloubert
var newStr = StringFormat.format("{0:upper} {1:lower}",
                                 "Marcel", "KlOUBERT");

The ctx object of a provider callback has the following structure:

Name	Description
expression	The expression right to :. In that example upper and lower.
handled	Defines if value was handled or not. Is (false) by default.
value	The value that should be parsed. In that example Marcel and KlOUBERT.

The parsed value has to be returned and ctx.handled has to be set to (true).

All upcoming format providers will be skipped if the value has been marked as "handled".