11.Essay
- indexOf
- lastIndexOf
- charAt
- trim
- lenght
- startsWith
- endsWith
- padStrad
- padEnd
- replace
- replaces
- search
- slice
- substring
- substr
- trimStart
- trimend
- includes
- search
append
prepend
replaceWith
after
before
appendChild
insertBefore
replaceChild(node）
removeChild()