数组，字符串，对象，数组对象之间的相互转换

var searchConditions = [
          {
            model: '0',
            option: [
                {
                  value: 'applying',
                  label: '待审批'
                },
            ]
          },
        ]
JSON.stringify(searchConditions)
// "[{"model":"0","option":[{"value":"applying","label":"待审批"}]}]"
JSON.stringify(searchConditions).indexOf('applying')
// 34


var a = ["1","2"];
a.join(" ")     //"1 2"