const arr = [1, 2, 3, 4, 5, 6]
arr.forEach(function (item, key, arr) {
console.log(item)
return item
})
console.log('---------------')
let result = arr.map(function (item, key, arr) {
return item * 2
})
console.log(result)
console.log('---------------')
arr.every(function (item) {
console.log(item > 0)
})
console.log(arr.every(item => item > 0))
console.log(arr.every(item => item > 3))
console.log(arr.some(item => item > 3))
console.log(arr.some(item => item > 10))
console.log('---------------')
console.log(arr.filter(item => item > 3))
console.log(arr.filter(item => item > 3)[0])
console.log(arr.filter(item => item > 3)[1])
console.log(arr.find(item => item > 3))
console.log(arr.findIndex(item => item > 3))
console.log('-----------------')
result = arr.reduce(function (acc, cur, key, arr) {
return acc + cur
}, 0)
console.log(result)
result = arr.reduce(function (acc, cur, key, arr) {
console.log(`acc=${acc}, cur=${cur}, key=${key},arr=${arr}`)
return acc + cur
}, 0)
console.log(result)
console.log('---------------------')
result = arr.reduceRight(function (acc, cur) {
console.log('<li>' + acc + '</li>')
return acc + cur
}, '')
console