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      <th>Population (M)</th>
      <th>GNP (B)</th>
    <tr><td>United Kingdom</td><td>64.231</td><td>2290</td></tr>




 *Functional JavaScript for crawling the Web

/*************************************************** *
 * Helper Fantion

function logs(){
	return arguments;

function nodes(sel, root){
	return (root || document).querySelectorAll(sel);

function finder(selector) {
  return function(root) {
    return nodes(selector, root);

function map(fn, iterable){
	return [], fn)

function prop(name){
	return function(object){
		return object[name];

function sequence() {
	var fns =;
	return fns.reduce(function(comp, fn) {
		return function(){
			var args =;
			return comp(fn.apply(null, args))

//隣り合う 2 つの配列要素に対して(左から右へ)同時に関数を適用
function reduce(fn, init, iterable){
	return [], fn, init)

function compose(){
	var fns =;
	return sequence.apply(null, fns.reverse());

function curry( orig_func ) {
	var ap = Array.prototype;
	var args = arguments;
	function fn() {
		ap.push.apply( fn.args, arguments );
		return fn.args.length < orig_func.length
		  ? fn
		  : orig_func.apply( this, fn.args );
	return function() {
		fn.args = args, 1 );
		return fn.apply( this, arguments );

function partial( orig_func ) {
	var aps = Array.prototype.slice,
	args = arguments, 1 );
	return function() {
		return orig_func.apply( this, args.concat( arguments ) ) );

 * 以下、main

var  rows = nodes("tbody tr");
var findCells = finder("td");
var getText = prop("textContent");

var getFirst = prop(0);
var getSecond = prop(1);
var getThird = prop(2);

 * テーブルの1行目(国名)を取得
console.log( "first-ColumnList", map(compose(findCells, getFirst, getText), rows) )

 * 途中の処理にlogsを挟んでデバッグ
console.log( "debug", map(compose(findCells, getFirst, logs, getText), rows) )

 * 人口の合計を取得
var sum = function(a, b) {
	return a + b;
var populations  =  map(compose(findCells, getSecond, getText, parseFloat), rows);
console.log("sum-populations", reduce(sum, 0, populations));

 * データをオブジェクトに変換
var asObject = function(data){
	return {
		population: parseFloat(getSecond(data)),
var getTexts = partial(map, getText); //getText関数をmap関数に部分適用して、arrayにgetTextを使えるようにする
console.log("toObject",  map(compose(findCells, getTexts, asObject), rows ))