JavaScriptで一致部分一致存在チェックのメソッド全解説！

let 一致した添字 = 配列.indexOf( 存在確認したい値 )

const fruits = ["banana", "orange", "grape"];
const found = fruits.indexOf("grape");
console.log(found);
> 2

const array = [1,2,3,4,5]
function gt3(value){
   return value > 2;
}

const newArray = array.filter(gt3);
console.log(newArray);
> [3,4,5]

let 切り取られた配列 = 元の配列.slice([開始位置 , 終了位置]);

const fruits = [ "banana", "orange", "grape"];
const newfruits = fruits.slice(1,2);
console.log(newFruits);
> ["orange"]

let 真偽値 = 配列.includes(存在確認したい値);

const fruits = ["banana", "orange", "grape"]
const found = fruits.includes("grape");
console.log(found)
> true

let 結果 = 配列.every((value, index, array) => {
  return 真偽値
}[,_this];

const army = [1,2,3,4,5]
function gt2(value) = {
  return value > 0
}

const result1 = army.every(value => value > 0)
console.log(result1);
>true

const result2 = army.every(gt2)
cosole.log(result2)
> true

let 結果 = 配列.some((value, index, array) => {
  return 真偽値
}[,_this]

const arry = [1,2,3,4,5];
const result = army.some(value => value > 4);
console.log(result);
> true

let 条件を満たす最初の値 = 配列.find(( value, index, array) => {
   return 真偽値
}[,_this]

const array = [1,2,7,8,9];
const result = array.find(value => value > 2);
console.log(result);
> 7