Develop Reference

How to output an array in Javascript like a social media feed?

I'm using React for my application and I've put my data (objects) into an array. Is there a way to output my data (array of objects) that loads all at once (such as Twitter, Instagram, Facebook)?
Currently I'm using a for loop where it loads one by one from my latest post to the end.
Here's a sample for loop to demonstrate.
var myArray = [
{name: 'Dwayne', age: 28},
{name: 'Rob', age: 32},
{name: 'Marie', age: 22},
{name: 'Sarah', age: 40},
{name: 'Emma', age: 29},
{name: 'James', age: 30}
];
for (var i = myArray.length - 1; i >= 0; i--){
console.log(myArray[i].name, myArray[i].age);
}

Here's an example of using map to generate a <p/> element with name and age inside it.
render(){
const myArray = [
{name: 'Dwayne', age: 28},
{name: 'Rob', age: 32},
{name: 'Marie', age: 22},
{name: 'Sarah', age: 40},
{name: 'Emma', age: 29},
{name: 'James', age: 30}
];
return(
<div>
{myArray.map((item, index) => (
<p key={`${item.name}-${index}`}>
Name:{item.name}, Age:{item.age}
</p>
))}
</div>
)
}
The above code would output
<div>
<p>Name:Dwayne, Age:28</p>
<p>Name:Rob, Age:32</p>
<p>Name:Marie, Age:22</p>
<p>Name:Sarah, Age:40</p>
<p>Name:Emma, Age:29</p>
<p>Name:James, Age:30</p>
</div>

Grouping nested dada

Say you have csv data file like this:
name, age
Bob, 27
George, 25
Bill, 22
Henry,27
Carol,25
Mary, 28
Harold,27
Jane, 25
I want to aggregate totals by age for a bar chart. So that I get totals like this: age 27(3), age 25(2), etc.
I am using d3 v4

As mentioned in the comments, you could use d3.nest:
const data = [
{name: 'Bob', age: 27},
{name: 'George', age: 25},
{name: 'Bill', age: 2},
{name: 'Henry', age: 27},
{name: 'Carol', age: 25},
{name: 'Mary', age: 28},
{name: 'Harold', age: 27},
{name: 'Jane', age: 25},
];
console.log(d3.nest()
.key(d => d.age)
.rollup(results => results.length)
.entries(data));
<script src="https://cdnjs.cloudflare.com/ajax/libs/d3/4.13.0/d3.min.js"></script>

sorting feature in ngTable using Jasmine Testing

I have created an application using ng-table , the application is working fine but i don'nt know how to write a test case for that sorting and getData.
Can anyone please tell me some solution for testing that functionality
My code is as given below
jasmine test case
describe('Testing Controllers', function() {
describe('Testing WorkController Controller', function() {
var WorkController, $scope;
beforeEach(module('wsd'));
beforeEach(inject(function($controller, $rootScope) {
$scope = $rootScope.$new();
WorkController = $controller('WorkController', {
$rootScope: $rootScope,
$scope: $scope,
ngTableParams : ngTableParams,
$filter: $filter
});
}));
it('should tableParams when tableParams is called', function() {
});
});
});
workstation/main.js
angular.module('wsd.workstations', [])
.controller('WorkController', function($rootScope, $scope, $filter, ngTableParams)
{
$scope.myValues = [{name: "Moroni", age: 50},
{name: "Tiancum", age: 43},
{name: "Jacob", age: 27},
{name: "Nephi", age: 29},
{name: "Enos", age: 34},
{name: "Tiancum", age: 43},
{name: "Jacob", age: 27},
{name: "Nephi", age: 29},
{name: "Enos", age: 34},
{name: "Tiancum", age: 43},
{name: "Jacob", age: 27},
{name: "Nephi", age: 29},
{name: "Enos", age: 34},
{name: "Tiancum", age: 43},
{name: "Jacob", age: 27},
{name: "Nephi", age: 29},
{name: "Enos", age: 34}];
$scope.tableParams = new ngTableParams({
sorting: {
name: 'asc'
}
}, {
getData: function($defer, params) {
$scope.myValues = $filter('orderBy')($scope.myValues, params.orderBy());
$defer.resolve($scope.myValues);
}
});
$scope.searchDocuments = function()
{
// some other logic
};
});
Update 2
I have done like this for testing, but getting
<failure type="">TypeError: &apos;undefined&apos; is not a function (evaluating &apos;$defer.resolve($scope.myValues)&apos;)
test cases
it('should check tableParams getData sorting', inject(function($q) {
var deferred = $q.defer();
var promise = deferred.promise;
promise.then(function(result) {
expect(result).toEqual(expectedResult);
});
$scope.myValues = [{name: "Moroni", age: 50},
{name: "Tiancum", age: 43},
{name: "Jacob", age: 27},
{name: "Nephi", age: 29},
{name: "Enos", age: 34},
{name: "Tiancum", age: 43},
{name: "Jacob", age: 27},
{name: "Nephi", age: 29},
{name: "Enos", age: 34},
{name: "Tiancum", age: 43},
{name: "Jacob", age: 27},
{name: "Nephi", age: 29},
{name: "Enos", age: 34},
{name: "Tiancum", age: 43},
{name: "Jacob", age: 27},
{name: "Nephi", age: 29},
{name: "Enos", age: 34}];
$scope.getData(promise, $scope.tableParams );
}));

You could:
Declare getData function on controller's $scope, thus making it available in your test:
$scope.tableParams = new ngTableParams({
sorting: {
name: 'asc'
}
}, {
getData: $scope.getData
});
$scope.getData = function($defer, params) {
$scope.myValues = $filter('orderBy')($scope.myValues, params.orderBy());
$defer.resolve($scope.myValues);
}
Inject $q in beforeEach().
Create a promise object using $q.
Assign some $scope.myValues for your unit test.
Declare a variable containing your expected result - that is your sorted $scope.myValues array. Then:
promise.then(function(result){
expect(result).toEqual(expectedResult);
}
$scope.getData(deferred , $scope.tableParams);

Passing java script function result to Angular ng-table

I have Angular ng-table where I load Json data to $data variable and display in the table.
function ngTable(){
var app = angular.module('main', ['ngTable']).
controller('DemoCtrl', function($scope, ngTableParams) {
var data = [{name: "Moroni", age: 50},
{name: "Tiancum", age: 43},
{name: "Jacob", age: 27},
{name: "Nephi", age: 29},
{name: "Enos", age: 34},
{name: "Tiancum", age: 43},
{name: "Jacob", age: 27},
{name: "Nephi", age: 29},
{name: "Enos", age: 34},
{name: "Tiancum", age: 43},
{name: "Jacob", age: 27},
{name: "Nephi", age: 29},
{name: "Enos", age: 34},
{name: "Tiancum", age: 43},
{name: "Jacob", age: 27},
{name: "Nephi", age: 29},
{name: "Enos", age: 34}];
$scope.tableParams = new ngTableParams({
page: 1, // show first page
count: 10 // count per page
}, {
total: data.length, // length of data
getData: function($defer, params) {
$defer.resolve(data.slice((params.page() - 1) * params.count(), params.page() * params.count()));
}
});
});
}
Additionally I have Java Script function returning some other Json data - function is called on button click.
function ReturnJson() {
var json = [];
$('body').on('click','button#test', function(){
var id = $(this).attr("value").val();
json = id;
});
return json;
}
How do I replace var data content with ReturnJson() every time on button click action ?

Simple assignment will work, but remember to reload the grid:
$scope.loadData = function () {
$scope.data = $scope.ReturnJson();
$scope.tableParams.reload();
}
$scope.ReturnJson = function () {
var json = [{name: "bb", age: 200},{name: "aaa", age: 100}];
return json;
}
Here is a working demo: http://plnkr.co/edit/Jw41uCmHGAfjkuoLIQor?p=preview

How can I update a row in a javascript array based on a key value?

I have an array of data like this:
var nameInfo = [{name: "Moroni", age: 50},
{name: "Tiancum", age: 43},
{name: "Jacob", age: 27},
{name: "Nephi", age: 29},
{name: "Enos", age: 34}];
If I have an object like this:
var nameInfo = {name: "Moroni", age: 51};
Is there a simple way that I can update the variable nameInfo. The key
between these is the name column. I know there is a way that I could
do this by searching for the row, removing and adding but I would like
to have a way to do this where I updated the row. Note that if it helps I do have underscore.js loaded.

Easiest way is to just loop over and find the one with a matching name then update the age:
var newNameInfo = {name: "Moroni", age: 51};
var name = newNameInfo.name;
for (var i = 0, l = nameInfo.length; i < l; i++) {
if (nameInfo[i].name === name) {
nameInfo[i].age = newNameInfo.age;
break;
}
}
JSFiddle Example
Using underscore you can use the _.find method to do the following instead of the for loop:
var match = _.find(nameInfo, function(item) { return item.name === name })
if (match) {
match.age = newNameInfo.age;
}
JSFiddle Example

Edit:
You can use ES6 filter combined with arrow functions
nameInfo.filter(x => {return x.name === nametofind })[0].age = newage
You can use _.where function
var match = _.where(nameInfo , {name :nametofind });
then update the match
match[0].age = newage

var nameInfo = [{name: "Moroni", age: 50},{name: "Tiancum", age: 43},
{name: "Jacob", age: 27},{name: "Nephi", age: 29},
{name: "Enos", age: 34}
];
_.map(nameInfo, function(obj){
if(obj.name=='Moroni') {
obj.age=51; // Or replace the whole obj
}
});
This should do it. It's neat and reliable and with underscore

Using Underscore you can use _.findWhere http://underscorejs.org/#findWhere
_.findWhere(publicServicePulitzers, {newsroom: "The New York Times"});
=> {year: 1918, newsroom: "The New York Times",
reason: "For its public service in publishing in full so many official reports,
documents and speeches by European statesmen relating to the progress and
conduct of the war."}

You can use findWhere and extend
obj = _.findWhere(#songs, {id: id})
_.extend(obj, {name:'foo', age:12});

You can use the _.find method, like this:
var nameInfos = [{name: "Moroni", age: 50},
{name: "Tiancum", age: 43},
{name: "Jacob", age: 27},
{name: "Nephi", age: 29},
{name: "Enos", age: 34}];
var nameToSearch = "Moroni";
var myRecord = _.find(nameInfos, function(record){ return record.name === nameToSearch; });
Working example: http://jsfiddle.net/9C2u3/

var match = _.findWhere(nameInfo , {name :nametofind });
match.age = newage

A staright forward using lodash's find() function,
var nameInfo = [{name: "Moroni", age: 50},
{name: "Tiancum", age: 43},
{name: "Jacob", age: 27},
{name: "Nephi", age: 29},
{name: "Enos", age: 34}];
var objToUpdate = _.find(nameInfo, {name: "Moroni"});
if(objToUpdate) objToUpdate.age = 51;
console.log(nameInfo); // Moroni age will be 51;
Note: If there are multiple Moroni objects, _.find can fetch the first match only.