数组扩展新增的特性实例详解

{
  let arr = Array.of(3,4,7,9,11);
  console.log('arr=',arr);//[3,4,7,9,11]

  let empty=Array.of();//[]
  console.log('empty',empty);
}

{
  let p=document.querySelectorAll('p');
  let pArr=Array.from(p);
  pArr.forEach(function(item){
    console.log(item.textContent);
  });

  console.log(Array.from([1,3,5],function(item){return item*2}));//[2,6,10]
}

{
  console.log('fill-7',[1,'a',undefined].fill(7));//[7,7,7]
  console.log('fill,pos',['a','b','c'].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('values',index,value);
  }
}

{
  console.log([1,2,3,4,5].copyWithin(0,3,4));//[4,2,3,4,5]
}

{
  console.log([1,2,3,4,5,6].find(function(item){return item>3}));//4
  console.log([1,2,3,4,5,6].findIndex(function(item){return item>3}));
}

{
  console.log('number',[1,2,NaN].includes(1));//true
  console.log('number',[1,2,NaN].includes(NaN));//true
}