// ES5循环实现 some 方法

const selfSome = function (fn, context) {

let arr = Array.prototype.slice.call(this)

// 空数组直接返回 false，数组的 every 方法则相反返回 true

if(!arr.length) return false

for (let i = 0; i < arr.length; i++) {

if(!arr.hasOwnProperty(i)) continue;

let res = fn.call(context,arr[i],i,this)

if(res)return true

}

return false

}

Array.prototype.selfSome ||(Object.defineProperty(Array.prototype, 'selfSome', {

value: selfSome,

enumerable: false,

configurable: true,

writable: true

}))

let arr = [1, 2, 3, 4, 5]

console.log(arr.selfSome(item => item === 2))