what is ... in javascript
function sum(...numbers) {
return numbers.reduce((accumulator, current) => {
return accumulator += current;
});
};
sum(1,2) // 3
sum(1,2,3,4,5) // 15
what is ... in javascript
function sum(...numbers) {
return numbers.reduce((accumulator, current) => {
return accumulator += current;
});
};
sum(1,2) // 3
sum(1,2,3,4,5) // 15
~~ in javascript
~~'-1' = -1
~~true = 1
~~false = 0
~~5.6 = 5
... in javascript
function sum(x, y, z) {
return x + y + z;
}
const numbers = [1, 2, 3];
console.log(sum(...numbers));
// expected output: 6
console.log(sum.apply(null, numbers));
// expected output: 6
/* Spread syntax (...) allows an iterable such as an array expression or string
to be expanded in places where zero or more arguments (for function calls)
or elements (for array literals) are expected, or an object expression to be
expanded in places where zero or more key-value pairs (for object literals)
are expected. */
// ... can also be used in place of `arguments`
// For example, this function will add up all the arguments you give to it
function sum(...numbers) {
let sum = 0;
for (const number of numbers)
sum += number;
return sum;
}
console.log(sum(1, 2, 3, 4, 5));
// Expected output: 15
// They can also be used together, but the ... must be at the end
console.log(sum(4, 5, ...numbers));
// Expected output: 15
what is javascript
// Function: creates a new paragraph and appends it to the bottom of the HTML body.
function createParagraph() {
let para = document.createElement('p');
para.textContent = 'You clicked the button!';
document.body.appendChild(para);
}
/*
1. Get references to all the buttons on the page in an array format.
2. Loop through all the buttons and add a click event listener to each one.
When any button is pressed, the createParagraph() function will be run.
*/
const buttons = document.querySelectorAll('button');
for (let i = 0; i < buttons.length ; i++) {
buttons[i].addEventListener('click', createParagraph);
}
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