javascript - 为什么我的 JS 对象最终具有“未定义”值？

Question

var testRuleInput = {
    "ruleName" : "renderDataVerificationFields",
    "dependencies" : [
        {
            "fieldName" : "mailingStreetAddress",
            "resource" : "verificationResults",
            "attribute" : "verifyStreetAddress"
        }
    ]
};

但是，当我后来打电话时console.log(testRuleInput.dependencies.attribute)；我明白了undefined。使困惑！

Answer 1

dependencies是一个对象数组。

更新您的代码：

console.log(testRuleInput.dependencies[0].attribute)

或者删除数组语法：

"dependencies": {
    "fieldName": "mailingStreetAddress",
    "resource": "verificationResults",
    "attribute": "verifyStreetAddress"
}

Answer 2

这是因为dependencies是一个数组。我想你正在寻找testRuleInput.dependencies[0].attribute.

Answer 3

您正在使用数组。

testRuleInput.dependencies[0].attribute

如果您只想要 1 个依赖项或像上面那样正确索引它，请删除方括号。

var testRuleInput = {
                        "ruleName" : "renderDataVerificationFields",
                        "dependencies" : {
                            "fieldName" : "mailingStreetAddress",
                            "resource" : "verificationResults",
                            "attribute" : "verifyStreetAddress"
                        }
                   };

Answer 4

testRuleInput.dependencies是一个数组。如果你使用testRuleInput.dependencies[0].attribute你会得到你所期望的。