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12-advanced-functions.html
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12-advanced-functions.html
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<!DOCTYPE html>
<html lang="en">
<head>
<title>Advanced Functions</title>
</head>
<body>
<button onclick="" class="js-button">Click</button>
<script>
const buttonElement = document.querySelector('.js-button');
const eventListener = () => {
connsole.log('click');
}
// does same thing as onclick but allows you to add multiple listeners
buttonElement.addEventListener('click', ()=>{
console.log('click');
});
buttonElement.removeEventListener('click', () => {})
buttonElement.addEventListener('click', ()=>{
console.log('click2');
});
/*
const nums = 2;
// anonymous function (function with no name)
const function1 = function() {
console.log('hello2');
}
console.log(function1);
console.log(typeof function1);
// functions are values in javascript
// so we can store values in objects
const object1 = {
num: 2,
fun: function() {
console.log('hello3');
}
};
object1.fun();
function display(param) {
console.log(param);
}
display(2);
// passing in a function inside a function
// the following regular function syntax allows hoisting which means that the function can be used anywhere before it is actually made.
function run(param) {
}
run(function() {
console.log('hello4');
});
*/
/*
// asynchronous Code: computer wont wait for the following line to finish to continue
setTimeout(function(){
console.log('timeout')
}, 3000);
console.log('next line');
// will keep running function every 3 seconds
setInterval(function(){
console.log('interval')
}, 3000);
*/
/*
[
'make dinner',
'wash dishes',
'watch youtube'
].forEach((value, index) => {
if (value === 'wash dishes'){
return;
}
console.log(index);
console.log(value);
});
const regularFunction = function(param, param2) {
console.log('Hello');
return 5;
}
const arrowFunction = (param, param2) => {
console.log('hello');
return 5;
};
arrowFunction();
const oneParam = (param) => {
console.log(param +1);
};
oneParam(2);
const oneLine = () => 2+3;
console.log(oneLine());
*/
// in filter if the return value is true then the value is added to new array otherwise it isn't.
[1,-3,5].filter((value, index) => {
/*
if (value >= 0){
return true;
}
else{
return false;s
}
*/
return value >= 0;
})
// map will transform an array into another array based on return values
[1,1,3].map((value, index) => {
return value *2;
});
// closure= if a function has access to a value it will always have access to that function. so even if an index value is deleted after a loop the function will still have access to the index.
</script>
</body>
</html>