React.useEffect(() => {
if (foo){
// do something
}
})
React.useEffect(() => {
if (!foo){
return;
}
// do something
})
Here is what the above code is Doing:
1. The first useEffect is called every time the component renders.
2. The second useEffect is called only when the component mounts and when foo changes.
function returnMe() { for (var i = 0; i < 2; i++) { if (i === 1) return i; } } console.log(returnMe()); Here is what the above code is Doing: 1. The function returnMe is defined. 2. The function returnMe is called. 3. The function returnMe is executed. 4. The for loop is executed. 5....
Iterable l = json.decode(response.body); List posts = List.from(l.map((model)=> Post.fromJson(model))); Here is what the above code is Doing: 1. We are using the http package to make a GET request to the URL. 2. We are using the json.decode() method to decode the JSON string into a List object. 3. We are using the List.from() method…
Yup.string().matches(/^\d+$/, { message: ” }); Here is what the above code is Doing: 1. We’re using the Yup library to create a schema. 2. We’re using the shape() method to create a schema that has a single property called “name”. 3. We’re using the string() method to specify that the “name” property should be a…
const mockCallback = jest.fn(x => 42 + x); forEach([0, 1], mockCallback); // The mock function is called twice expect(mockCallback.mock.calls.length).toBe(2); Here is what the above code is Doing: 1. Create a mock function with jest.fn(). 2. Pass that mock function as a prop to the component you want to test. 3. Inside the test, render the…
let obj = { name:”FreeCodeCamp” review:”Awesome” }; Object.freeze(obj); obj.review = “bad”; //will be ignored. Mutation not allowed obj.newProp = “Test”; // will be ignored. Mutation not allowed console.log(obj); // { name: “FreeCodeCamp”, review:”Awesome”} Here is what the above code is Doing: 1. We create an object called obj. 2. We use Object.freeze to freeze obj….
$(‘#example’).dataTable( { “drawCallback”: function( settings ) { alert( ‘DataTables has redrawn the table’ ); } } ); Here is what the above code is Doing: 1. The first line is the standard way to initialize a DataTable. 2. The second line is the drawCallback function. This function is called every time the table is drawn….