SOURCE

let arr =['a','b','c','_cc'];
let reg = new RegExp(`^\\_`);
let c = reg.test('_cc')
console.log(c)
let m = arr[3].replace(reg,'')
console.log('m',m)
let s = arr.reduce((result,item)=>{
  console.log('item' , JSON.stringify(result))
  if(reg.test(item)){
    
    result[item.replace(reg,'')] = 'hello world';
  }
  return result
},{})

console.log('asdfasdfasdf',JSON.stringify(s))

<p>hello</p>