数组 、 字符串 简单去重

var arr = [1,2,5,3,4,4,4,4,4,4];
var obj = {}
for(var i  in arr){
   obj[arr[i]] = 100;
}
console.log( obj);

　　es6：

	var arr = [1,2,3,4,4,2,4,45,6,6,7,7,"dff","dff",'7',{'dd':'dd'}];
	console.log(...new Set(arr));

　　

	var arr = [5,2,3,6,8,6,5,4,7,1,9];
	var arrB = [];
	for(var i = 0; i<arr.length; i++){
		console.log(arr[i]);
		if(arrB.indexOf(arr[i]) == -1){
			arrB.push(arr[i]);
		}
	}
	console.log(arrB);

　　

字符串 去重：

    //声明变量
        var str = "aaaaaaa2222ffff";
	var str1 = "";
	var flag = false;
	for(var i = 0; i < str.length; i++) {
		var c = str.charAt(i);
		if(str.indexOf(c) == str.lastIndexOf(c)) {
			flag = false;

		} else {
			flag = true;
		}
		if(i == str.indexOf(c)) {
			flag = true;
			if(flag) {
				str1+=c;
			}
		}
	}

	console.log(str1);