Js常用方法函数，工具等

/**
 * Convert a style object to a string
 * @param   { Object } style - style object we need to parse
 * @returns { String } resulting css string
 * @example
 * styleObjectToString({ color: 'red', height: '10px'}) // => 'color: red; height: 10px'
 */
function styleObjectToString(style) {
  return Object.keys(style).reduce(function (acc, prop) {
    return (acc + " " + prop + ": " + (style[prop]) + ";")
  }, '')
}

/**
 * Faster String startsWith alternative
 * @param   { String } str - source string
 * @param   { String } value - test string
 * @returns { Boolean } -
 */
function startsWith(str, value) {
  return str.slice(0, value.length) === value
}