Access JSON element by key using nodejs - returns undefined [duplicate]

How can I access Array value using the key name in nodejs? I'm getting undefined when trying to access it following way. I want the value to be print when calling the key.

   var sns_DimensionsValue  = sns.Trigger.Dimensions['ApiName']
   console.log(sns_DimensionsValue)

Json Data:

{
    "AlarmName": "Zabbix PY 5XX - ByName",
    "AlarmDescription": null,
    "AWSAccountId": 123456789",
    "NewStateValue": "ALARM",
    "NewStateReason": "Threshold Crossed: 1 out of the last 1 datapoints [1.0 (11/11/21 13:51:00)] was greater than or equal to the threshold (1.0) (minimum 1 datapoint for OK -> ALARM transition).",
    "StateChangeTime": "2021-11-11T13:52:09.318+0000",
    "Region": "Asia Pacific (Mumbai)",
    "AlarmArn": "arn:aws:cloudwatch:ap-south-1:123456789:alarm:Zabbix PY 5XX - ByName",
    "OldStateValue": "INSUFFICIENT_DATA",
    "Trigger": {
        "MetricName": "5XXError",
        "Namespace": "AWS/ApiGateway",
        "StatisticType": "Statistic",
        "Statistic": "MINIMUM",
        "Unit": null,
        "Dimensions": [
            {
                "value": "zabbixPy-API",
                "name": "ApiName"
            }
        ],
        "Period": 60,
        "EvaluationPeriods": 1,
        "ComparisonOperator": "GreaterThanOrEqualToThreshold",
        "Threshold": 1,
        "TreatMissingData": "- TreatMissingData:                    missing",
        "EvaluateLowSampleCountPercentile": ""
    }
}