YQL finance data

examples.js

YQL('yahoo.finance.quotes')
  .where({ symbol: [ '^IXIC'  ] })
  .select([ 'Symbol', 'LastTradePriceOnly', 'Change', 'PercentChange' ])
  .then(function (results) {
    console.log(results)
  })

YQL('yahoo.finance.historicaldata')
    .where('symbol', '=', 'PRFC')
    .where({ startDate: new Date(2015, 4, 1), endDate: new Date(2015, 4, 23) })
    .then(function (results) {
      console.log(results)
    })

yql.js

(function () {
  function YQL (table) {
    return new QueryBuilder(table)
  }

  var defaults = {
    baseUrl: 'http://query.yahooapis.com/v1/public/yql',
    env: 'store://datatables.org/alltableswithkeys',
  }

  function exec (options) {
    if (is('string', options)) {
      options = { q: options }
    }
    options =  $.extend({}, defaults, options)
    return $.getJSON(options.baseUrl, {
      q: options.q,
      env: options.env,
      format: 'json'
    }).then(function (response) {
      return response.query.results.quote
    })
  }

  YQL.exec = exec
  YQL.defaults = defaults

  function QueryBuilder (table) {
    this.table = table
    this.keys = []
    this.clauses = []
  }

  QueryBuilder.prototype.then = function (a, b) {
    return this.exec().then(a, b)
  }

  QueryBuilder.prototype.exec = function () {
    return exec({ q: this.toString() })
  }

  QueryBuilder.prototype.select = function (keys) {
    this.keys = this.keys.concat(keys)
    return this
  }

  QueryBuilder.prototype.where = function (a, op, b) {
    switch (arguments.length) {
    case 3:
      return this.where(a + ' ' + op + ' ' + param(b))
    case 2:
      return this.where(a, (is('array', op) ? 'in' : '='), op)
    case 1:
      if (is('string', a)) {
        this.clauses.push(a)
      } else {
        Object.keys(a).forEach(function (key) {
          this.where(key, a[key])
        }, this)
      }
      return this
    default:
      throw new Error('expected 1 to 3 arguments')
    }
  }

  QueryBuilder.prototype.toString = function () {
    var q = []
    var keys = this.keys.slice(0)
    if (!keys.length) { keys.push('*') }
    q.push('select', keys.join(','))
    q.push('from', this.table)
    if (this.clauses) {
      q.push('where', this.clauses.join(' and '))
    }
    return q.join(' ')
  }

  function param (value) {
    var type = $.type(value)
    switch (type) {
    case "string":
      return '"' + value + '"'
    case "number":
      return param(String(value))
    case "array":
      return '(' + value.map(param).join(',') + ')'
    case "date":
      var parts = [
        value.getFullYear(),
        pad(value.getMonth() + 1, 2),
        pad(value.getDate(), 2)
      ]
      return param(parts.join('-'))
    }
  }

  function pad (x, len) {
    var str = String(x || 0)
    while (str.length < (len || 0)) { str = '0' + str }
    return str
  }

  function is (typ, val) {
    return $.type(val) == typ
  }

  window.YQL = YQL
})();