想限制用户存储的历史记录数量比如10个10个后的新添加的排在最前面的同时也会删除一个旧的数据

SearchBtn.onclick = function(){
let userVal = SearchInput.value;
let localCon = localStorage.getItem('SearchInputValue');
arr = localStorage.getItem('SearchInputValue') ? arr = JSON.parse(localStorage.getItem('SearchInputValue')) : [];
if(userVal == null||userVal == ''||userVal == undefined||userVal == false){
return userVal;
}else{
let arr = [];
}
arr.unshift(userVal);
localStorage.setItem('SearchInputValue',JSON.stringify(arr));
};

arr = localStorage.getItem('SearchInputValue') ? arr = JSON.parse(localStorage.getItem('SearchInputValue')) : [];
if(arr.length >= 10) {
  arr.splice(9, 1, '最新值')
} else {
  arr.push('最新值')
}
 localStorage.setItem('SearchInputValue', JSON.stringify(arr))