hn job query search

hn_seach.js

// takes arguments and produces an array of functions that accept context
function handle_args() {
  var args = Array.prototype.slice.call(arguments);
  return args.map(function(arg) {
    if(arg instanceof Function) return arg; // Presumably already a contex-accepting function.
    if(arg instanceof Array) return and.apply(this, arg); // make arrays behave as and.
    // Presuming a string, build a function to check.
    var my_regex = new RegExp(arg.toString(), 'i');
    return function(context) {
      return context.search(my_regex) > -1;
    };
  });
}

// Perform a logical and on any number of arguments.
function and() {
  var args = handle_args.apply(this, arguments);
  return function(context) {
    return args.every(function(a) {return a(context);});
  }
}

// Perform a logical not. This function is also the NAND function, so accepts multiple arguments.
function not() {
  var result = and.apply(this, arguments);
  return function(context) {
    return !result(context);
  }
}

nand = not;

// Performs an or using De Morgan's laws
function or() {
  var args = handle_args.apply(this, arguments);
  return nand.apply(this, args.map(function(a) {return not(a)}));
}

// Performs an XOR. This only works for two inputs.
function xor() {
  if(arguments.length != 2) throw "XOR takes two arguments only.";
  return and(or.apply(this, arguments), not(and.apply(this, arguments)));
}

function query() {
  var 
    total = 0, shown = 0,
    // HN is done with very unsemantic classes.
    job_list = Array.prototype.slice.call(document.querySelectorAll('.c5a,.cae,.c00,.c9c,.cdd,.c73,.c88')),
    query = or.apply(this, arguments);
    
  // This traverses up the dom stack trying to find a match of a specific class
  function up_to(node, klass) {
    if (node.className === klass) {
      return node;
    } 
    if(node === document.body) {
      throw new Exception();
    }
    return up_to(node.parentNode, klass);
  }

  function display(node, what) {
    up_to(node, 'athing').style.display = what;
  }
  
  // Check each job for a match, and show it if it matches.
  job_list.forEach(function(node) {
    if(query(node.innerHTML)) {
      display(node, 'block');
      shown ++;
    } else display(node, 'none');
    total ++;
  });
  return {shown: shown, total: total}
}