jPaq Example - Currying Up String Functions

You ever wonder how libraries such as jPaq and Prototype add prototype functions to different classes? At for jPaq, it isn't by relying on the curry function. Perhaps it should be though. The following example shows that you can use the curry function to produce trim, trimLeft, trimRight, addSlashes, and surroundWith, each with just one line of code. In the example, I also added two casing functions with minimal effort to the string prototype. Execute the code below and see the result of running these functions:

// Setup aliases.
var p = String.prototype, r = p.replace;

// Add the trim functions.
p.$trimLeft = r.curry(/^[\u00A0\s]+/g, "");
p.$trimRight = r.curry(/[\u00A0\s]+$/g, "");
p.$trim = r.curry(/^[\u00A0\s]+|[\u00A0\s]+$/g, "");

// Add backslashes to escape special characters.
p.$addSlashes = r.curry(/([\\"'])/g, "\\$1");

// Add the specified characters to the beginning and end of the string.
p.$surroundWith = r.curry(/^|$/g);

// Add the proper casing function.
p.$toProperCase = r.curry(/(^|[\u00A0\s])[^\u00A0\s]/g, function(a) {
  return a.toUpperCase();
});

// Add the opposite casing function.
p.$toOppositeCase = r.curry(/[^\u00A0\s]/g, function(a) {
  return a.toUpperCase() == a ? a.toLowerCase() : a.toUpperCase();
});

// Try out all of the new functions.
alert("This text is quoted.".$surroundWith('"'));
alert("   This is left trimmed.   ".$trimLeft().$surroundWith('"'));
alert("   This is right trimmed.   ".$trimRight().$surroundWith('"'));
alert("   This is fully trimmed.   ".$trim().$surroundWith('"'));
alert("title case".$toProperCase().$surroundWith('"'));
alert("oPPoSiTe cAsE".$toOppositeCase().$addSlashes().$surroundWith('"'));
alert("Escaped single quote:  '".$addSlashes());
alert('Escaped double quote:  "'.$addSlashes());
alert("Escaped backslash:  \\".$addSlashes());

Applicable Parts

Function.prototype.curry()

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