Personal summary of some commonly used javascript functions

functionextend(target, ... rest) {for(let i = 0; i < rest.length; i++) {
    let source = rest[i]
    for(let key in source) {
      target[key] = source[key]
    }
  }
  return target
}

var inBrowser = typeof window ! = ='undefined'
var ua = inBrowser && navigator.userAgent.toLowerCase()
var isWeChatDevTools = ua && /wechatdevtools/.test(ua)
var isAndroid = ua && ua.indexOf('android'Var elementStyle = 0inBrowser && document.createElement('div').style
var vendor = (function () {
  if(!inBrowser) {
    return false
  }
  var transformNames = {
    standard: 'transform',
    webkit: 'webkitTransform',
    Moz: 'MozTransform',
    O: 'Otransform',
    ms: 'msTransform'
  }

  for(let key in transformNames) {
    if(elementStyle[transformNames[key]] ! == undefined) {return key
    }
  }
})()

function prefixStyle(style) {
  if(vendor === false) {return false}
  if(vendor === 'standard') {
    if(style === 'transitionEnd') {
      return 'transitionend'
    }
    return style
  }
  return vendor + style.charAt(0).toUpperCase() + style.substr(1)
}

function addEvent(el, type, fn, capture) {
  el.addEventListener(type, fn, {passive: false, capture: !! capture}) }function removeEvent(el, type, fn, capture) {
  el.removeEventListener(type, fn, {passive: false, capture: !! capture}) }let transform = prefixStyle('transform')
let transition = prefixStyle('transition')

var hasPerspective = inBrowser && prefixStyle('perspective') in elementStyle
var hasTouch = inBrowser && ('ontouchstart' inwindow || isWeChatDevTools) var hasTransform = transform ! = =false
var hasTransition = inBrowser && transition in elementStyle
var style = {
  transform,
  transition,
  transitionTimingFunction: prefixStyle('transitionTimingFunction'),
  transitionDuration: prefixStyle('transitionDuration'),
  transitionDelay: prefixStyle('transitionDelay'),
  transformOrigin: prefixStyle('transformOrigin'),
  transitionEnd: prefixStyle('transitionEnd')}function prepend(el, target) {
  if (target.firstChild) {
    before(el, target.firstChild)
  } else {
    target.appendChild(el)
  }
}

function before(el, target) {
  target.parentNode.insertBefore(el, target)
}

functionRemoveChild (el, child) {el.removechild (child)} // Add the class nameexport function addClass(el, className) {
  if(hasClass(el,className)) {
    return
  }
  let newClass = el.className.split(' ')
  newClass.push(className)
  el.className = newClass.join(' '} // Determine whether a class is includedfunction hasClass(el, className) {
  let reg = new RegExp('(^|\\s)' + className+'(\\s|$)')
  return reg.test(el.className)
}

function getData(el, name, val) {
  name = `data-${name}`
  if(val) {
    return el.setAttribute(name, val)
  } else {
    return el.getAttribute(name)
  }
}

function getNow() {
  return window.performance && window.performance.now 
    ? (window.performance.now() + window.performance.timing.navigationStart()) : new Date()
}
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