国家为何要求所有网站均须备案,wordpress安装上传,网站建设使用虚拟主机的优点与缺点,5网站建设Array.from //将可迭代对象或字符串转换为数组
console.log(Array.from(1234)); //[ 1, 2, 3, 4 ]Array.isArray //判断是否是数组
Array.isArray([1])//trueArray.concat //用于合并两个或多个数组。此方法不会更改现有数组#xff0c;而是返回一个新数组
let arr [1,2,3]… Array.from //将可迭代对象或字符串转换为数组
console.log(Array.from(1234)); //[ 1, 2, 3, 4 ]Array.isArray //判断是否是数组
Array.isArray([1])//trueArray.concat //用于合并两个或多个数组。此方法不会更改现有数组而是返回一个新数组
let arr [1,2,3]
let arr2 [4,5,6,7]
console.log(arr.concat(arr2)) //[1,2,3,4,5,6,7]Array.copyWithin // 改变原数组 copyWithin(target,start,end)
let arr [0,1,2,3]
console.log(arr.copyWithin(2,1)) //[ 0, 1, 1, 2 ]let arr [0,1,2,3]
console.log(arr.copyWithin(2,10)) //[ 0, 1, 2, 3 ]Array.entries //返回一个新的数组迭代器对象该对象包含数组中每个索引的键/值对
let arr [0,1,2,3]
let arr2 arr.entries()
console.log(arr2.next()) //{ value: [ 0, 0 ], done: false }
console.log(arr2.next()) //{ value: [ 1, 1 ], done: false }
console.log(arr2.next()) //{ value: [ 2, 2 ], done: false }
console.log(arr2.next()) //{ value: [ 3, 3 ], done: false }
console.log(arr2.next()) //{ value: undefined, done: true }Array.every //测试一个数组内的所有元素是否都能通过指定函数的测试。返回布尔值
let arr [0,1,2,3]
let arr2 arr.every((v){return v 4
})
console.log(arr2); //trueArray.fill //用一个固定值填充一个数组中从起始索引默认为 0到终止索引默认为 array.length内的全部元素。它返回修改后的数组
let arr [0,1,2,3]
console.log(arr.fill(4)); //[ 4, 4, 4, 4 ]let arr [0,1,2,3]
console.log(arr.fill(4,1)); //[ 0, 4, 4, 4 ] 从下标1开始填充let arr [0,1,2,3]
console.log(arr.fill(4,1,3)); //[ 0, 4, 4, 3 ] 下标1到下标3填充Array.filter //过滤
let arr [0,1,2,3]
let arr2 arr.filter(v{return v!1
})
console.log(arr2); //[ 0, 2, 3 ]Array.find let arr [a,b,c,d]
let arr2 arr.find(v{return v c
})
console.log(arr2); //cArray.findIndex let arr [a,b,c,d]
let arr2 arr.findIndex(v{return v c
})
console.log(arr2); //2Array.findLast let arr [a,b,c,d,a,b,c,d]
let arr2 arr.findLast(v{return v c
})
console.log(arr2); //cArray.findLastIndex let arr [a,b,c,d,a,b,c,d]
let arr2 arr.findLastIndex(v{return v c
})
console.log(arr2); //6Array.forEach let arr [a,b,c,d]
arr.forEach((v,i){console.log(v,i);
})
//a 0
//b 1
//c 2
//d 3Array.flat //数组扁平化
let arr [a,[b,[c,[d,[e,[f]]]]]]
console.log(arr.flat()); //[ a, b, [ c, [ d, [Array] ] ] ]
console.log(arr.flat(2)); //[ a, b, c, [ d, [ e, [Array] ] ] ]
console.log(arr.flat(3)); //[ a, b, c, d, [ e, [ f ] ] ]
console.log(arr.flat(Infinity)); //[ a, b, c, d, e, f ]Array.includes let arr [a,b,c,d]console.log(arr.includes(b)) //trueArray.indexOf let arr [a,b,c,d]console.log(arr.indexOf(a)) //0console.log(arr.indexOf(ab)) //-1Array.isArray let arr [a,b,c,d]console.log(Array.isArray(arr)) //trueArray.join let arr [a,b,c,d]console.log(arr.join(,)) //a,b,c,dArray.lastIndexOf let arr [a,b,c,a,b,c]console.log(arr.lastIndexOf(b)) //4console.log(arr.lastIndexOf(1)) //-1Array.length let arr [a,b,c]console.log(arr.length) //3Array.map let arr [a,b,c]let arr2 arr.map(v{return v1})console.log(arr2) //[ a1, b1, c1 ]Array.pop //从数组中删除最后一个元素并返回该元素的值。此方法会更改数组的长度let arr [a,b,c]console.log(arr.pop()) //cconsole.log(arr); //[ a, b ]Array.push //将指定的元素添加到数组的末尾并返回新的数组长度csharplet arr [a,b,c]console.log(arr.push(d)) //4console.log(arr); //[ a, b, c, d ]Array.reduce //对数组中的每个元素按序执行一个提供的 reducer 函数每一次运行 reducer 会将先前元素的计算结果作为参数传入最后将其结果汇总为单个返回值
let arr [1,2,3,4,5,6]
arr.reduce((a,b){console.log(a,b);return ab
})
//1 2
//3 3
//6 4
//10 5
//15 6
//21let arr [1,2,3,4,5,6]
arr.reduce((a,b){console.log(a,b);return ab
},10)
//10 1
//11 2
//13 3
//16 4
//20 5
//25 6
//31 Array.reverse let arr [1,2,3,4,5,6]
console.log(arr.reverse()) //[ 6, 5, 4, 3, 2, 1 ]Array.shift let arr [1,2,3,4,5,6]
console.log(arr.shift()) //1
console.log(arr); //[ 2, 3, 4, 5, 6 ]Array.slice let arr [1,2,3,4,5,6]
console.log(arr.slice()) //[ 1, 2, 3, 4, 5, 6 ]
console.log(arr.slice(2)) //[ 3, 4, 5, 6 ]
console.log(arr.slice(2,4)) //[ 3, 4 ]Array.some let arr [1,2,3,4,5,6]
let arr2 arr.some(v{return v 3
})
console.log(arr2); //trueArray.sort let arr [a,d,e,b,c,f]
let arr2 arr.sort()
console.log(arr2); //[ a, b, c, d, e, f ]let arr [1,2,6,7,8,3,4,5,9,10]
let arr2 arr.sort((a,b){return a-b
})
console.log(arr2); //[1,2,6,7,8,3,4,5,9,10]Array.splice let arr [1,2,3,4,5,6,7,8,9,10]
arr.splice(3) //[ 1, 2, 3 ]
arr.splice(3,6) //[ 1, 2, 3, 10 ]
arr.splice(3,6,a) //[1,2,3,a,8,9,10]Array.unshift let arr [1,2,3]
arr.unshift(0)
console.log(arr); //[ 0, 1, 2, 3 ]
