false
text="aaaa1111"
"aaaa1111"
pattern=/\d+/g
text.search(pattern)
4
text.match(pattern)
text.replace(pattern,"2222")
"aaaa2222"
text.split(/\D+/)
Array [ "", "1111" ]
0!==0
false
null!=undefined
false
null!==undefined
true
null==undefined
true
null===undefined
false
var s="1111";
function f(){
console.log(s)
var s=‘2222‘
console.log(s)
}
