1、数组去重
Array.prototype.DuplicateRemoval = function(){
let res = [this[0]];
for(let i = 1; i < this.length; i++){
var repeat = false;
for(let j = 0; j < res.length; j++){
if(this[i] == res[j]){
repeat = true;
break;
}
}
if(!repeat){
res.push(this[i]);
}
}
return res;
}
var arr = [1, '1', '1', 'b', 'd', 'e', 'e', 1, 0]
console.log(arr.DuplicateRemoval());
2、页面刷新前触发
window.addEventListener("beforeunload", function(event) {
event.returnValue = "You may have unsaved Data";
});