Here list some Javascript Array methods witch helpful and useful to my work
some & every
let users = [{name: 'foo',age: 18},{name: 'bar',age: 21}]
users.some((user)=>user.age < 20) // true
users.every((user)=>user.age < 20) // false
-
somejust returntrueifusershas one user age < 20 -
everyjust return true if allusersage < 20
splice
// splice(index[, deleteCount, elem1, ..., elemN])
const fruits = ['apple','pera','grape']
fruits.splice(1,1,'pineapple','watermelon') // ['pera']
// fruits: ['apple','pineapple','watermelon','grape']
splice method will return modified array elements but will mutation origin array. fruits will be ['apple','pineapple','watermelon','grape']
Args
-
indexwhich started index you will mutation -
deleteCountwill declare how many element you will replaced -
elem1,...eleNwill afterindexpoistion
unshift & push
const fruits = ['apple','pera','grape']
fruits.unshift(...['pineapple']) // will return fruits length 4
console.log(fruits) // (4) ["pineapple", "apple", "pera", "grape"]
fruits.push('watermelon') // will return fruits length 5
console.log(fruits) //(5) ["pineapple", "apple", "pera", "grape", "watermelon"]
-
unshfit(...item)will push item to beginning of array -
push(item)will push item to end of array
forEach
["foo", "bar", "zzzzz"].forEach((item, index, array) => {
console.log(`${item} is at index ${index} in ${array}`);
});
Usual we just pass first two args item, index but array used when you need referer the iterate object here is ["foo", "bar", "zzzzz"]
find & findIndex
const fruits = ['apple','pera','grape']
fruits.find((fruit)=> fruit==='apple') // apple
fruits.findIndex((fruit)=> fruit==='grape') // 2
// if not found will return -1
fruits.findIndex((fruit)=> fruit==='notfound') // -1
-
findwill return the first matched element infruits -
findIndexwill return the first matched element index atfruitsarray
filter
const fruits = ['apple','pera','grape']
let results = fruits.filter((fruit) => fruit.length > 4) // (2) ["apple", "grape"]
fileter will return new array witch iterate callback return true
map
let items = ["foo", "bar", "zzz"].map(item => `lol:${item}`);
console.log(items); // (3) ["lol:foo", "lol:bar", "lol:zzz"]
We can use map transform array element and return new array
Not limited to the above method aslo includes: reverse, reduce, concat ,slice , join
Hope it can help you :)
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