JSFiddle - React, Tailwind, and code Playground

HTML

<button id="test">See the Tab</button>
<div class="varianceData"></div>

JavaScript

$('#test').click(function () {

    // Here are the two dates to compare
    var date1 = '29-10-2015';
    var date2 = '29-12-2015';
    var Targetvalue = parseFloat("1000000");
    var dealjson = '[{"dealdate":"25-11-2015","cost":200000}]';

    // First we split the values to arrays date1[0] is the year, [1] the month and [2] the day
    date1 = date1.split('-');
    date2 = date2.split('-');
    
    // Now we convert the array to a Date object, which has several helpful methods
    date1 = new Date(date1[2], date1[1], date1[0]);
    date2 = new Date(date2[2], date2[1], date2[0]);
    var deals = JSON.parse(dealjson);
    var achieved = 0;

    var str = '<table> <tr> <th>Week</th> <th>Target</th> <th>Achieved</th> </tr>'; 
    
    var i = 0;
    while(date1 <= date2) {
    	var next_week = new Date(date1);
        next_week.setDate(date1.getDate() + 7); 
        achieved = 0;
        deals.forEach(function(deal){
        	var dealDate = deal.dealdate;
            dealDate = dealDate.split('-');
            dealDate = new Date(dealDate[2], dealDate[1], dealDate[0]);
            if (dealDate >= date1 && dealDate <= next_week) {
            	achieved = achieved + deal.cost;
            }
        });
        i = i + 1;
        date1 = next_week;
        str = str + "<tr><th>Week" + i + "</th><td>" + Targetvalue + "</td><td> " + achieved +  "</td></tr>";
    }
    
 

    str = str + "</table>";
    $('.varianceData').html(str);

});