SOURCE

const featureConfig = {
    "feature":{
        "persona_user_xxx":{"featureData":[{"element_type":1,"update_timestamp":1631682616.604203,"id":3,"label_id":13252,"feature_value":"[21,22]","value_type":1,"update_period":100,"user_id":5035210211,"type":10,"feature_identifier":"persona_user_13252"}]}
    }
};

  // feature：需要处理的特征，键值对对象
  // params: 特征处理的其他参数，键值对对象
  const { feature, params } = featureConfig;
  var scale = 20;
  var data = {featureData: null};
//   data['feature']=feature;
  var featureDataArray = new Array();
  var stringArray = new Array();
  data.featureData = featureDataArray;
  
 for(var featureName in feature) {
    var info = feature[featureName];
    var featureData = info.featureData;
    if (featureData instanceof Array && featureData.length > 0) {
        for(var row in featureData) {
            for(var key in featureData[row]) {
                if (key == "feature_value") {
                    var value = featureData[row][key];
                    if(Number(value)){
                        featureData[row][key] = value * scale;
                    }else if(typeof(value) == "string"){
                        stringArray=value.replace (/\[|]/g, "").split(",")
                        for(var num in stringArray){
                            stringArray[num]=stringArray[num]*scale
                        }
                        featureData[row][key] =stringArray;
                    }
                    data = info;    
                }
            }
        }
    }
    featureDataArray = featureDataArray.concat(featureData);
}
 data.featureData = featureDataArray;
 console.log(data);