javascript-learner/5.4ArrayMethod/t.js
2024-06-16 21:03:42 +02:00

37 lines
1.0 KiB
JavaScript

array = ["Bilbo", "Gandalf", "Nazgul"];
array.forEach((item, index, array) =>{
console.log(`${item} is at index ${index} in ${array}`)
});
console.log(`arr.indexOf(Bilbo): ${array.indexOf("Bilbo")}`)
console.log(`arr.indexOf(Bilbo): ${array.includes("Bilbo")}`)
let fruits = ['Apple', 'Orange', 'Apple']
console.log(`fruits.indexOf('Apple'): ${fruits.indexOf('Apple')}`)
console.log(`fruits.lastIndexOf('Apple'): ${fruits.lastIndexOf('Apple')}`)
// arr.find(fn)
let users = [
{id: 1, name: "xingzhesun"},
{id: 2, name: "zhexingsun"},
{id: 3, name: "sunxingzhe"},
];
let user1 = users.find(item => item.id == 1);
let user2 = users.findLastIndex(item => item.id == 1);
console.log(user1.name);
console.log(user2.name);
// arr.filter
let someUsers = users.filter(user => user.id < 3);
console.log(someUsers)
someUsers = users.filter(function(item, index, array){
if (item.id < 3){
return true;
}
})
console.log(someUsers);
// arr.map(fn)
let lengths = array.map(item=>item.length);
alert(lengths);