Rename Object Key in an array using javascript

Use the map function:

var array = [{"id":"5","name":"Immidiate"},
{"id":"4","name":"30 days"},
{"id":"3","name":"21 days"},
{"id":"2","name":"14 days"},
{"id":"1","name":"7 days"},
{"id":"6","name":"Custom"}];

var resultArray = array.map(function(elm) {
   return { Name: elm[widget.seriesname], Data: elm[widget.dataname]};
});

const arr = [{"id":"5","name":"Immidiate"},
{"id":"4","name":"30 days"},
{"id":"3","name":"21 days"},
{"id":"2","name":"14 days"},
{"id":"1","name":"7 days"},
{"id":"6","name":"Custom"}];

const resultArray = arr.map(elm => ({ Name: elm.id, Data: elm.name}));

console.log(resultArray);

EDIT: Just seen your angular tag - use angular's forEach:

var out = [];

angular.forEach(data, function (obj) {
    out.push({
        Name: obj.id,
        Data: obj.name
    });
});

Without angular:

For modern browsers, use array.map:

var out = data.map(function (obj) {
   return {
        Name: obj.id,
        Data: obj.name
    };
});

console.log(out);

And in older browsers:

var data = [{"id":"5","name":"Immidiate"},
           {"id":"4","name":"30 days"},
           {"id":"3","name":"21 days"},
           {"id":"2","name":"14 days"},
           {"id":"1","name":"7 days"},
           {"id":"6","name":"Custom"}];

var out = [];

for (var key in data) {
    if (data.hasOwnProperty(key)) {
        out.push({
            'Name': data[key].id,
            'Data': data[key].name
        });
    }
}

console.log(out);