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联合调试过程中,设备调用某云端API打印报错:
TypeError: Cannot read property ‘length’ of undefined
单元测试指定的API过程中,发现复现规律,马上用Node.js写了一个Demo测试,找出根因。
var jsonInfo = {
"room":[
{"name":"t1", "value":"10"},
{"name":"t2", "value":"10"}
],
};
var json = JSON.stringify(jsonInfo);
console.log(json);
console.log(typeof json);
var backToJs = JSON.parse(json);
console.log(backToJs);
console.log(backToJs.room.length);
// 当上传的数据,room字段不存在的时候,去访问.room.length就会出错
TypeError: Cannot read property 'length' of undefined
at Object.<anonymous> (/node.js-tutorial/p19.js:18:38)
at Module._compile (module.js:652:30)
at Object.Module._extensions..js (module.js:663:10)
at Module.load (module.js:565:32)
at tryModuleLoad (module.js:505:12)
at Function.Module._load (module.js:497:3)
at Function.Module.runMain (module.js:693:10)
at startup (bootstrap_node.js:188:16)