vue对象比较，阻止后退

变量

data() {
      return {
        flag: false,
        form: {
          title: '',
          subtitle: "",
        },
    }
}

方法

    beforeRouteLeave(to, from, next) {
      //let one= JSON.parse(JSON.stringify(this.form));
      let one = JSON.stringify({title: "1", subtitle: "2"});
      let two = JSON.stringify({title: "1", subtitle: "3"});

      console.log(window.performance.navigation.type);
      console.log(window.history.length);
      if (one !== two && !this.flag) {
        next(false);
        setTimeout(() => {
          this.Confirm("数据没有保存，确定要退出吗？", () => {
            this.flag = true;
            if (window.performance.navigation.type === 2) {
              window.history.go(-1)
            } else if (window.performance.navigation.type === 1) {
              this.$router.push({path: to.path})
            }
          }, () => {
          });
        }, 500)
      } else {
        next()
      }
    }

// confirm
        Confirm(text,ok,close){
            this.$confirm(text, '提示', {
                confirmButtonText: '确定',
                cancelButtonText: '取消',
                type: 'warning'
              }).then(() => {
                if(ok){
                    ok()
                }
              }).catch(() => {
                if(close){
                    close()
                }
              });
 },

 数组去重

 const arr = ['张三', '张三', '三张三']
    // set 自带去重
    let set = new Set(arr)
    console.log(set)
    // [ '张三', '三张三' ]
    console.log(Array.from(set))

    let person = [
      {id: 0, name: '小明'},
      {id: 1, name: '小张'},
      {id: 2, name: '小李'},
      {id: 3, name: '小孙'},
      {id: 1, name: '小周'},
      {id: 2, name: '小陈'}
    ]
    // 数组对象去重
    let obj = {}
    // 设置cur默认类型为数组，并且初始值为空的数组
    let peon = person.reduce((cur, next) => {
      obj[next.id] ? '' : obj[next.id] = true && cur.push(next)
      return cur
    }, [])
    console.log(peon)

 eval的使用

var o = eval("({name:'kaka',age:19})")
console.log(o.name)

var str1 = '{ "name": "kaka", "sex": "man" }';

var obj = JSON.parse(str1); //由JSON字符串转换为JSON对象
console.log(obj);
console.log(typeof (obj));

var obj2 = eval('(' + str1 + ')'); //由JSON字符串转换为JSON对象
console.log(obj2);
console.log(typeof (obj2));

var last = JSON.stringify(obj); //将JSON对象转化为JSON字符
console.log(last);
console.log(typeof (last));

Funtion

function foo() {
   console.log("foo")
}

// 等价于
var func = Function("console.log("foo")");
func()

var func = Function(foo());
func()

function cmp(a, b, c) {
   return Math.max(a, b, c)
}

var max = new Function('a', 'b', 'c', 'return cmp(a, b, c)')
console.log(max(11, 22, 33));

function Foo() {
    }

    // foo.prototype.sayHello = function (a) {
    //     console.log(a)
    // }
    Foo.prototype = {
        func: function () {
            console.log("func")
        },
        sayHello: function (a) {
            console.log(a)
        }
    };

    var p = new Foo();
    p.sayHello("sayHello");
    p.func();


    var o = {
        go: function () {
            console.log("go")
        }
    };
    var o1 = Object.create(o);
    o1.go();


    var list = Object.create([]);
    list.push("A");
    list.push("B", "C", "D", "E", "F", "G");
    for (let i = 0; i < list.length; i++) {
        console.log("" + i + "" + ": " + list[i])
    }

函数科里化（高阶函数）

function foo() {
        var num = Math.random();

        function func() {
            return num;
        }

        return func;

    }

    var f = foo();
    var res1 = f();
    var res2 = f();

    console.log(res1);
    console.log(res2);



    function goo() {
        var o = {name: "kaka"};
        return function () {
            return o;
        }
    }

    var g = goo();
    var ret = g();
    console.log(ret.name);
    // 函数科里化（高阶函数）
    console.log(goo()());



    function hoo() {
        var num = Math.random();
        return {
            get_num: function () {
                return num;
            },
            set_num: function (value) {
                num = value;
            }
        }
    }

    var t = hoo();
    var num = t.get_num();
    console.log(num);

    t.set_num(1);
    num = t.get_num();
    console.log(num);