tiny-sprintf

Tiny but complete.

• Implements sprintf based on the php doc. They have some nice examples.
• Is only 550B minified (I guess that's even less gzipped).
• By default only supports conversion type s, but that can be easily extended. I don't really see why you need these conversions when everything gets typecasted to string anyway.

Format

The full format (where [] means optional element) is:

"%[+][index$]['padchar][-][minWidth][.maxWidth]type"

Explanation of elements:

1. %
   • defines the start of a substring to interpret.
2. +
   • if type is d and positive, prepend value with a + character. Not implemented by default.
3. index$
   • where index is an integer.
   • Points to argument to use as value.
   • Default is using an index, starting at 1, that is incremented with each replace done.
   • Note: 0$ will point to the string to replace, and you probably don't want that.
4. 'padchar
   • where padchar is a single character of any kind.
   • It must be preceded by a single quote (').
   • Default is " "
   • Note: define your string with double qoutes and everything will be fine. If padchar is zero (0), you can leave out the quote.
5. -
   • If added, the value gets left aligned.
   • Default is is right aligned.
   • Note: only makes sense with minWidth or maxWidth defined.
6. minWidth
   • where minWidth is an integer.
   • If the value (see index$) in string form is shorter than this, the rest gets filled up with the padchar. It's added on the left or right of value, depending on the alignment setting (see -).
7. .maxWidth
   • where maxWidth is an integer.
   • If the value with padding is longer than this value, it gets cut off. Alignment is the same as with minWidth.
8. type
   • where type is a string s, but this collection can be extended.
   • Does typecasting on the value before it is converted to string. Most of the times, you will probably just want to use s

Adding conversion types

Punch functions into the sprintf function under the same property as the type character. Expect args value, plusChar and return the value in the desired format. You don't have to convert it to string.

For example, adding d (typecast to Number, add plus if desired) is like:

sprintf.d = function(value, plusChar) {
    return (plusChar || '') + (+value);
};

Most times, you will not need plusChar.

Examples

sprintf.d = function(value, plusChar) {
    return (plusChar || '') + (+value);
};
// Type casting...
sprintf('%s', 10); // '10'
sprintf('%s', 'abc'); // 'abc'
sprintf('%d', 12); // '12'
sprintf('%d', 'abc'); // 'NaN'

// Limit length
sprintf("%.5s", 'abcdef'); // 'bcdef'
sprintf("%-.5s", 'abcdef'); // 'abcde'

// Indent to length
sprintf("%5s", 'a'); // '    a'
sprintf("%-5s", 'a'); // 'a    '
sprintf("%5.4s", 'abc'); // ' abc'
sprintf("%-5.4s", 'abc'); // 'abc '

// Use pad chars
sprintf("%04s", 10); // "0010"
sprintf("%'#4s", 10); // "##10"

// Use arguments in order
sprintf("%1$s, %2$s, %2$s, %1$s!", 'left', 'right'); // 'left, right, right, left!'

// Escape anything else
sprintf('%%', 1); // '%'
sprintf('%T', 'abc'); // 'T'