數組擴展
數組新增特性
- Array.from
- Array.of
- copyWithin
- find / findIndex
- fill
- entries / keys / values 遍歷相關
- includes
{
let arr = Array.of(1,2,4,5,6);
console.log('arr=', arr)
let empty = Array.of()
console.log('empty',empty)
}
{
let p = document.querySelectorAll('p');
let pArr = Array.from(p);
pArr.forEach(function(item,index){
console.log(item.textContent)
})
console.log(Array.from([1,3,5],function(item){return item+2}));
}
{
console.log('fill-7',[1,'a',undefined].fill(7));
console.log('fill,pos',["a","b","c","d","e"].fill(7,1,3));
}
{
for(let index of ['1','c','ks'].keys()){
console.log('keys',index)
}
for(let value of ['1','c','ks'].values()){
console.log('values', value)
}
for(let [index,value] of ['1','c','ks'].entries()){
console.log('index+values',index,value)
}
}
{
console.log([1,2,3,4,5].copyWithin(0,3,4))
console.log([1,2,3,4,5].copyWithin(0,3))
console.log([1,2,3,4,5].copyWithin(0,2,5))
}
{
console.log([1,2,3,4,5,6].find(function(item){return item > 3}))
console.log([1,2,3,4,5,6].find(function(item){return item > 9}))
console.log([1,2,3,4,5,6].findIndex(function(item){return item > 3}))
console.log([1,2,3,4,5,6].findIndex(function(item){return item > 9}))
}
{
console.log('number',[1,2,NaN].includes(1))
console.log('number',[1,2,NaN].includes(NaN))
}