amt: "10.00"
email: "sam@gmail.com"
merchant_id: "sam"
mobileNo: "9874563210"
orderID: "123456"
passkey: "1234"
以上就是我要处理的JSON对象。我想检查merchant_id键是否存在。我尝试了下面的代码，但它不工作。有办法实现吗?
<script>
window.onload = function getApp()
{
var thisSession = JSON.parse('<?php echo json_encode($_POST); ?>');
//console.log(thisSession);
if (!("merchant_id" in thisSession)==0)
{
// do nothing.
}
else
{
alert("yeah");
}
}
</script>
当前回答
我稍微改变你的if语句和工作(也为继承的obj -看片段)
if(!("merchant_id" in thisSession)) alert("yeah");
var sessionA = { amt: "10.00", email: "sam@gmail.com", merchant_id: "sam", mobileNo: "9874563210", orderID: "123456", passkey: "1234", } var sessionB = { amt: "10.00", email: "sam@gmail.com", mobileNo: "9874563210", orderID: "123456", passkey: "1234", } var sessionCfromA = Object.create(sessionA); // inheritance sessionCfromA.name = 'john'; if (!("merchant_id" in sessionA)) alert("merchant_id not in sessionA"); if (!("merchant_id" in sessionB)) alert("merchant_id not in sessionB"); if (!("merchant_id" in sessionCfromA)) alert("merchant_id not in sessionCfromA"); if ("merchant_id" in sessionA) alert("merchant_id in sessionA"); if ("merchant_id" in sessionB) alert("merchant_id in sessionB"); if ("merchant_id" in sessionCfromA) alert("merchant_id in sessionCfromA");
其他回答
你可以这样做:
if("merchant_id" in thisSession){ /** will return true if exist */
console.log('Exist!');
}
or
if(thisSession["merchant_id"]){ /** will return its value if exist */
console.log('Exist!');
}
类型检查也适用:
if(typeof Obj.property == "undefined"){
// Assign value to the property here
Obj.property = someValue;
}
试试这个,
if(thisSession.hasOwnProperty('merchant_id')){
}
JS对象thisSession应该像这样
{
amt: "10.00",
email: "sam@gmail.com",
merchant_id: "sam",
mobileNo: "9874563210",
orderID: "123456",
passkey: "1234"
}
你可以在这里找到细节
我稍微改变你的if语句和工作(也为继承的obj -看片段)
if(!("merchant_id" in thisSession)) alert("yeah");
var sessionA = { amt: "10.00", email: "sam@gmail.com", merchant_id: "sam", mobileNo: "9874563210", orderID: "123456", passkey: "1234", } var sessionB = { amt: "10.00", email: "sam@gmail.com", mobileNo: "9874563210", orderID: "123456", passkey: "1234", } var sessionCfromA = Object.create(sessionA); // inheritance sessionCfromA.name = 'john'; if (!("merchant_id" in sessionA)) alert("merchant_id not in sessionA"); if (!("merchant_id" in sessionB)) alert("merchant_id not in sessionB"); if (!("merchant_id" in sessionCfromA)) alert("merchant_id not in sessionCfromA"); if ("merchant_id" in sessionA) alert("merchant_id in sessionA"); if ("merchant_id" in sessionB) alert("merchant_id in sessionB"); if ("merchant_id" in sessionCfromA) alert("merchant_id in sessionCfromA");
你可以试试if(typeof object !== 'undefined')
