如何使用保存属性名称的变量检查对象属性是否存在? [英] How to check if object property exists with a variable holding the property name?

问题描述

我正在检查对象属性是否存在，其中的变量包含相关属性名称.

I am checking for the existence of an object property with a variable holding the property name in question.

var myObj;
myObj.prop = "exists";
var myProp = "p"+"r"+"o"+"p";

if(myObj.myProp){
    alert("yes, i have that property");
};

这是 undefined 因为它正在寻找 myObj.myProp 但我希望它检查 myObj.prop

This is undefined because it's looking for myObj.myProp but I want it to check for myObj.prop

推荐答案

var myProp = 'prop';
if(myObj.hasOwnProperty(myProp)){
    alert("yes, i have that property");
}

或

var myProp = 'prop';
if(myProp in myObj){
    alert("yes, i have that property");
}

或

if('prop' in myObj){
    alert("yes, i have that property");
}

请注意，hasOwnProperty 不会检查继承的属性，而 in 会检查.例如 'constructor' in myObj 是真的，但 myObj.hasOwnProperty('constructor') 不是.

Note that hasOwnProperty doesn't check for inherited properties, whereas in does. For example 'constructor' in myObj is true, but myObj.hasOwnProperty('constructor') is not.

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