{
//Need to put in var or else val is assumed to be constant
//Can't use let, because let is scoped only for the block, so we won't be able to call it outside of the for loop.
//But val also will not be defined outside of this broader block
for (var val = 0; val < 20; val++) {
console.log('Hello World +', val) //NOT ${val}' because that's for inserting into text in md
}
return val
}
{
for(var i=0; i<10; i++){
console.log(`Iteration number ${i}`); // Remember that the output will show up in the Console.
}
return i
}
{
let array = [0, 1, 2, 3, 4]
for(var i in array){
array[i] = array[i] ** 2;
}
return array;
}
{
//while not best to use in most cases...but definitely use for recursion
var counter = 0;
while(counter < 5){
console.log(`The counter is ${counter}, which is less than 5.`)
counter += 1
};
return counter
}
{
//does what while loop does but with a for.
for(var i = 1; i<5; i++){
console.log('accessing an array', i) //prints to array
}
//can't access i here anymore since it was declared within for loop only
}
//Link to JS comparisons notationi: https://www.w3schools.com/js/js_comparisons.asp
{
const num = 100;
if(num == 100) {
return "100!"
}
else {
return "Not 100..."
}
}
{
let test = 80
if(test<50 || test == 3){
return 'this is a small number'
} else if (test>100){
return 'this is a very large number'}
else{
return 'this is medium number'
}
}
{
const num = 100;
if(num == 99) {
return "99!"
}
else {
return "Not 99..."
}
}
{var number = 100;
if(number == 100){
return "Number is 100";
} else if(number < 100){
return "Number is less than 100.";
} else if(number > 100){
return "Number is greater than 100.";
}};
// function declaration with parameters
function multiply_this(a,b) {
return a*b;
}
{
// call the function, providing arguments for the parameters
const x = 4;
const y = 5;
return multiply_this(x,y); // run function with x and y as our arguments
}
Type JavaScript, then Shift-Enter. Ctrl-space for more options. Arrow ↑/↓ to switch modes.
One platform to build and deploy the best data apps
Experiment and prototype by building visualizations in live JavaScript notebooks. Collaborate with your team and decide which concepts to build out.
Use Observable Framework to build data apps locally. Use data loaders to build in any language or library, including Python, SQL, and R.
Seamlessly deploy to Observable. Test before you ship, use automatic deploy-on-commit, and ensure your projects are always up-to-date.