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mixbo
mixbo

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Javascript Array methods used in my work

#javascript #tricks

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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
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  • some just return true if users has one user age < 20
  • every just return true if all users age < 20

splice 

// splice(index[, deleteCount, elem1, ..., elemN]) const fruits = ['apple','pera','grape'] fruits.splice(1,1,'pineapple','watermelon') // ['pera'] // fruits: ['apple','pineapple','watermelon','grape']
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splice method will return modified array elements but will mutation origin array. fruits will be ['apple','pineapple','watermelon','grape']

Args

  • index which started index you will mutation
  • deleteCount will declare how many element you will replaced
  • elem1,...eleN will after index poistion

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"]
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  • 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}`); });
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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
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  • find will return the first matched element in fruits
  • findIndex will return the first matched element index at fruits array

filter 

const fruits = ['apple','pera','grape'] let results = fruits.filter((fruit) => fruit.length > 4) // (2) ["apple", "grape"]
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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"]
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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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