原生 JavaScript 發送 Ajax 請求

Ajax

Asynchronous JavaScript + XML

做用

實現頁面的部分更新

寫法

var r = new XMLHttpRequest()
r.open(method, path)
r.onreadystatechange = function() {
  if (r.readyState == 4) {
    r.setRequestHeader('Content-Type', 'application/json')
    console.log('響應', r)
  }
}
r.send(data)

用法

訪問 https://weatherapi.market.xia... 運行下面代碼

var path = 'https://weatherapi.market.xiaomi.com/wtr-v3/weather/all?latitude=110&longitude=112&isLocated=true&locationKey=weathercn%3A101010100&days=15&appKey=weather20151024&sign=zUFJoAR2ZVrDy1vF3D07&romVersion=7.2.16&appVersion=87&alpha=false&isGlobal=false&device=cancro&modDevice=&locale=zh_cn'
var r = new XMLHttpRequest()
r.open('GET', path, true)
r.onreadystatechange = function() {
  if (r.readyState == 4) {
    var string =  r.responseText
    console.log('響應', JSON.parse(string))
  }
}
r.send()