HTML - create a text box with id ans. Run function getResponse() on key press

<input id = "ans" type="text" size="40" onkeypress="getresponse(event)">

JS

//create a function that receives an argument called event

function getResponse(event){

if (event.keyCode == 13) { // Number 13 stores the "Enter" key on the keyboard

var ua = input.value; //store the value in text box into a variable

if (parseInt(ua)==answer){

feedback.innerHTML="Well Done";

score+=1;

}

else{

feedback.innerHTML="That was incorrect. The correct answer was " + answer;

}

input.value = ""; //reset text box to blank

core.innerHTML = "score: " + score; //update the score output

}

}

Access a random element in the array using Math.round and Math.Random

//generate a random item from an array

var list =["a","b","c"]; //create a list of items

console.log(list[Math.round(Math.random()*3)]) // round off the random number to access the index of the array

Sort objects in an array by property name

var list =[

{id:1,name:"fred"},

{id:2,name:"ted"},

{id:3,name:"peg"},

];

//Below is an example of sorting the above object list by name.

list.sort((a, b) => (a.name > b.name) ? 1 : -1)

console.log(list);

Please note that all names need to be either lower or upper case as this will impact the alphabetical sort algorithm

Push a new object to an array using a function

var list =[

{id:1,name:"fred"},

{id:2,name:"ted"},

{id:3,name:"peg"},

];

add();

function add(){

list.push({id:1,name:"Sam"});

}

Add a new row to a HTML row and insert a value

function resultTable() {

var row = results_table.insertRow(-1); //add a new row to end of table

row.insertCell(0).innerHTML = "value"; //add new value to cell 1

row.insertCell(1).innerHTML = "value"; //add new value to cell 2

}

Delete a row from a Table

In the creation of the new table row - add a button and onclick listener in each row that says delete

<input type="button" value="Delete" onclick="deleteRow(this)">

Create a function to delete row in JS

Make sure you have global variable reference to your table

function deleteRow(r) {

var i = r.parentNode.parentNode.rowIndex;

table_name.deleteRow(i);

}

If you know the row number that you wish to delete:

table_name.deleteRow(2);

or if you created a const referencing the table at the top of your JS Note: -1 will delete the last row

table_name.deleteRow(-1);

Add and a remove a class style

In your css create a new css class.

.underline{

text-decoration:underline;

}

To edit a specific element and apply the class style to it

element_name.classList.add("underline");

To remove a specific elements class style:

element_name.classList.remove("underline");

Hide Element with space taken up

element_name.style.visibility= "hidden";

Show Element

element_name.style.visibility="visible";