JS遍历JSON数组及获取JSON数组长度操作示例【测试可用】

var questions = data.data.questionnaire.questions;
//遍历 json 数组
for (var i in questions) {
    if (questions[i].type == '(单选)') {
      alert('danxuan');
    }
}

function getJsonLength(json) {
  var jsonLength = 0;
  for (var i in json) {
    jsonLength++;
  }
  return jsonLength;
}

//简单json数组：
var jsonDemo ={"name":"\u811a\u672c\u4e4b\u5bb6","addtime":"2018-12-12","username":"jb51","id":5}
//遍历json数组：
for (var i in jsonDemo) {
  console.log(jsonDemo[i]);
}
//获取 JSON 数组长度：
function getJsonLength(json) {
  var jsonLength = 0;
  for (var i in json) {
    jsonLength++;
  }
  return jsonLength;
}
console.log('数组长度：'+getJsonLength(jsonDemo))