Typescript adaptation of http://stackoverflow.com/a/22818673/93964

StringHelpers.format

export class StringHelpers  {
    static format(format: string, ...args: any[]) : string {
        var i;
        if (args instanceof Array) {
            for (i = 0; i < args.length; i++) {
                format = format.replace(new RegExp('\\{' + i + '\\}', 'gm'), args[i]);
            }
            return format;
        }
        for (i = 0; i < arguments.length - 1; i++) {
            format = format.replace(new RegExp('\\{' + i + '\\}', 'gm'), arguments[i + 1]);
        }
        return format;
    }
}