如何检查JavaScript对象是否为JSON

我会检查构造函数属性。

例如

var stringConstructor = "test".constructor;var arrayConstructor = [].constructor;var objectConstructor = ({}).constructor;function whatIsIt(object) {    if (object === null) {        return "null";    }    if (object === undefined) {        return "undefined";    }    if (object.constructor === stringConstructor) {        return "String";    }    if (object.constructor === arrayConstructor) {        return "Array";    }    if (object.constructor === objectConstructor) {        return "Object";    }    {        return "don't know";    }}var testSubjects = ["string", [1,2,3], {foo: "bar"}, 4];for (var i=0, len = testSubjects.length; i < len; i++) {    alert(whatIsIt(testSubjects[i]));}

编辑：添加了一个空检查和一个未定义的检查。