JSFiddle - React, Tailwind, and code Playground

JavaScript

var response = {
    "result": "OK",
        "data": [{
        "number": "613-555-5555",
            "calls": 30
    }, {
        "number": "613-666-5555",
            "calls": 100
    }]
}
var data = response.data;
var length = response.length;
alert(data[0].number);
alert(data[0].calls);

for (var i = 0; i < data.length; i++) {
    var arrayItem = data[i];
    console.log(arrayItem);
}