Javascript 使用 jQuery 检查 JSON 对象中是否存在密钥
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Check if key exists in JSON object using jQuery
提问by nidhin
I have done AJAX validation and validated message is returned as a JSON array. Therefore I need to check whether the keys, like nameand email, are in that JSON array.
我已经完成了 AJAX 验证，并且经过验证的消息作为 JSON 数组返回。因此，我需要检查键（如name和email）是否在该 JSON 数组中。
{
"name": {
"isEmpty": "Value is required and can't be empty"
},
"email": {
"isEmpty": "Value is required and can't be empty"
}
}
Only if the key name is present, I need to write an error message to the namefield.
仅当键名存在时，我才需要向该name字段写入错误消息。
Following is the code to display an error if fields is entered
以下是在输入字段时显示错误的代码
if (obj['name']'isEmpty'] != "") {
$('#name').after(c1 + "<label class='error'>" + obj['name']['isEmpty'] + "</label>");
}
if (obj['email']['isEmpty'] != "" ) {
$('#email').after(c4 + "<label class='error'>" + obj['email']['isEmpty'] + "</label>");
}
But if the namefield is entered, it will not be in JSON array.
So the checking statement
但是如果name输入了该字段，它就不会在 JSON 数组中。所以检查语句
if (obj['name']['isEmpty'] != "")
will result in the following error:
将导致以下错误：
obj.name not found
找不到对象名称
It is not necessary to have key namein the array. At same time I need to check for this to display the error if the array possesses the key name.
没有必要name在数组中有键。同时，如果数组拥有 key ，我需要检查这个以显示错误name。
回答by Dau
Use JavaScript's hasOwnProperty()function:
使用 JavaScript 的hasOwnProperty()函数：
if (json_object.hasOwnProperty('name')) {
//do struff
}
回答by Pokuri
No need of JQuery simply you can do
不需要 JQuery 就可以了
if(yourObject['email']){
// what if this property exists.
}
as with any value for emailwill return you true, if there is no such property or that property value is nullor undefinedwill result to false
与任何值email将返回true，如果没有这样的属性或属性值null或undefined将导致以false
回答by jujiyangasli
if(typeof theObject['key'] != 'undefined'){
//key exists, do stuff
}
//or
if(typeof theObject.key != 'undefined'){
//object exists, do stuff
}
I'm writing here because no one seems to give the right answer..
我写在这里是因为似乎没有人给出正确的答案..
I know it's old...
我知道它很旧...
Somebody might question the same thing..
有人可能会质疑同样的事情..
回答by Vahap Gencdal
if you have an array
如果你有一个数组
var subcategories=[{name:"test",desc:"test"}];
function hasCategory(nameStr) {
for(let i=0;i<subcategories.length;i++){
if(subcategories[i].name===nameStr){
return true;
}
}
return false;
}
if you have an object
如果你有一个对象
var category={name:"asd",test:""};
if(category.hasOwnProperty('name')){//or category.name!==undefined
return true;
}else{
return false;
}
