JavaScript Code Contract Libraries?

Question

I am just starting up a new web application and I want to implement some form of contract\'esque style validation in my JavaScript. I did some quick googling, and came across Js

Answer 1

One more - https://www.npmjs.com/package/bycontract It's a small library that expects JSDoc expressions (http://usejsdoc.org/) for a contract. A good chance for you are already familiar with the syntax.

Just see it in action:

// Simple test
byContract( true, "boolean" ); // ok
// Multiple Types
byContract( 100, "string|number|boolean" ); // ok 
// Optional Parameters
function foo( bar, baz ) {
  byContract( arguments, [ "number=", "string=" ] );
}

Here kinda real-world example:

/**
 * @param {number|string} sum
 * @param {Object.} payload
 * @param {function} cb
 * @returns {HTMLElement}
 */
function foo( sum, payload, cb ) {
  // Test if the contract is respected at entry point 
  byContract( arguments, [ "number|string", "Object.", "function" ] );
  // .. 
  var res = document.createElement( "div" );
  // Test if the contract is respected at exit point 
  return byContract( res, HTMLElement );
}
// Test it 
foo( 100, { foo: "foo" }, function(){}); // ok 
foo( 100, { foo: 100 }, function(){}); // exception - ByContractError: Value of index 1 violates the contract `Object.`