Write a JavaScript method receiving an array of objects containing name+age+gender, returning everyone between 30 and 40 years old grouped by gender.

readme.txt

This code takes inputArr as an input and then does the following things :
1.identifies different gender values and makes set of them
2.puts name of a person against respective gender who is in age between 30-40, including 30 and 40.

Note : gender identification and creation of result object is done intentionally so that in case of more gender values and large set of data can be categorized automatically.

gistfile1.txt

var inputArr = [
    {'name':'paul', 'age':29, 'gender':'M'},
    {'name':'mike', 'age':35, 'gender':'M'},
    {'name':'john', 'age':30, 'gender':'F'},
    {'name':'ross', 'age':37, 'gender':'F'},
    {'name':'deny', 'age':42, 'gender':'NA'}
];

function getResultData(arr) {
   let returnData = [];
    arr.forEach(function (elem, index) {
        let genderIndex = -1;
        if(returnData.length === 0){
            returnData.push([]);
            returnData[returnData.length -1].push({'type':elem.gender});
            returnData[returnData.length -1].push({'data':[]});
            genderIndex = 0;
        }else{
            let addGenderFlag = true;
            for(let i=0, n = returnData.length; i<n;i++){
                addGenderFlag = false;
                if(returnData[i][0].type === elem.gender){
                    addGenderFlag = true;
                    genderIndex = i;
                    break;
                }
            }
            if(!addGenderFlag){
                returnData.push([]);
                returnData[returnData.length -1].push({'type':elem.gender});
                returnData[returnData.length -1].push({'data':[]});
                genderIndex = returnData.length - 1;
            }
        }
        if(filterArr(elem.age)) returnData[genderIndex][1].data.push(elem.name);
    });
    return returnData;
}

function filterArr(val){
    return ((val >= 30) && (val <= 40));
}

console.log(' result data : ' + JSON.stringify(getResultData(inputArr)));