如果我有对象的引用:
var test = {};
可能(但不是立即)具有嵌套对象,例如:
{level1: {level2: {level3: "level3"}}};
检查深度嵌套对象中是否存在属性的最佳方法是什么?
警报(测试级别1);生成未定义,但警告(test.level1.level2.level3);失败。
我目前正在做这样的事情:
if(test.level1 && test.level1.level2 && test.level1.level2.level3) {
alert(test.level1.level2.level3);
}
但我想知道是否有更好的方法。
我也遇到了同样的问题,我想看看是否能找到自己的解决方案。这接受要检查的路径作为字符串。
function checkPathForTruthy(obj, path) {
if (/\[[a-zA-Z_]/.test(path)) {
console.log("Cannot resolve variables in property accessors");
return false;
}
path = path.replace(/\[/g, ".");
path = path.replace(/]|'|"/g, "");
path = path.split(".");
var steps = 0;
var lastRef = obj;
var exists = path.every(key => {
var currentItem = lastRef[path[steps]];
if (currentItem) {
lastRef = currentItem;
steps++;
return true;
} else {
return false;
}
});
return exists;
}
下面是一些日志记录和测试用例的片段:
console.clear();var测试案例=[[“data.Messages[0].Code”,true],[“data.Messages[1].Code”,true],[“data.Messages[0]['Code']”,true],['data.Messages[0][“Code”]',true],[“data[Messages][0]['Code']”,错误],[“data['Messages'][0]['Code']”,真]];var path=“data.Messages[0].Code”;变量obj={数据:{消息:[{代码:“0”}, {代码:“1”}]}}函数checkPathForTruthy(obj,路径){if(/\[[a-zA-Z_]/.test(路径)){console.log(“无法解析属性访问器中的变量”);return false;}path=路径替换(/\[/g,“.”);path=路径替换(/]|'|“/g,”“);path=路径拆分(“.”);var步数=0;var lastRef=obj;var logOutput=[];var exists=path.every(key=>{var currentItem=lastRef[path[steps]];if(currentItem){logOutput.push(currentItem);lastRef=当前项;步骤++;返回true;}其他{return false;}});console.log(存在,logOutput);返回存在;}testCase.forEach(testCase=>{如果(checkPathForTruthy(obj,testCase[0])==testCase[1]){console.log(“通过:”+testCase[0]);}其他{console.log(“失败:”+testCase[0]+“预期”+testCase[1]);}});
根据@Stephane LaFlèche的回答,我提出了另一个剧本版本。
JSFiddle演示
var obj = {"a":{"b":{"c":"Hello World"}},"resTest":"potato","success":"This path exists"};
checkForPathInObject = function(object,path,value) {
var pathParts = path.split("."),
result = false;
// Check if required parameters are set; if not, return false
if(!object || typeof object == 'undefined' || !path || typeof path != 'string')
return false;
/* Loop through object keys to find a way to the path or check for value
* If the property does not exist, set result to false
* If the property is an object, update @object
* Otherwise, update result */
for(var i=0;i<pathParts.length;i++){
var currentPathPart = pathParts[i];
if(!object.hasOwnProperty( currentPathPart )) {
result = false;
} else if (object[ currentPathPart ] && path == pathParts[i]) {
result = pathParts[i];
break;
} else if(typeof object[ currentPathPart ] == 'object') {
object = object[ currentPathPart ];
} else {
result = object[ currentPathPart ];
}
}
/* */
if(typeof value != 'undefined' && value == result)
return true;
return result;
};
// Uncomment the lines below to test the script
// alert( checkForPathInObject(obj,'a.b.c') ); // Results "Hello World"
// alert( checkForPathInObject(obj,'a.success') ); // Returns false
// alert( checkForPathInObject(obj,'resTest', 'potato') ); // Returns true
//Just in case is not supported or not included by your framework
//***************************************************
Array.prototype.some = function(fn, thisObj) {
var scope = thisObj || window;
for ( var i=0, j=this.length; i < j; ++i ) {
if ( fn.call(scope, this[i], i, this) ) {
return true;
}
}
return false;
};
//****************************************************
function isSet (object, string) {
if (!object) return false;
var childs = string.split('.');
if (childs.length > 0 ) {
return !childs.some(function (item) {
if (item in object) {
object = object[item];
return false;
} else return true;
});
} else if (string in object) {
return true;
} else return false;
}
var object = {
data: {
item: {
sub_item: {
bla: {
here : {
iam: true
}
}
}
}
}
};
console.log(isSet(object,'data.item')); // true
console.log(isSet(object,'x')); // false
console.log(isSet(object,'data.sub_item')); // false
console.log(isSet(object,'data.item')); // true
console.log(isSet(object,'data.item.sub_item.bla.here.iam')); // true