js array先关的操作方法

const number = [1,4,7,3,6];
const number2 = [9,8];

console.log('删除数组中的第一个元素输出结果4，7，3，6', number.shift(),number);

console.log('删除数组中最后一个元素输出结果 7，3',number.pop());

console.log('在数组最开始插入数据', number.unshift(1));

console.log(number.concat(number2));

console.log(number2.reverse());

console.log(number2.join('-'));

const array1 = number.filter(function (value, index) {
    console.log(value,index);
    return value !== 1;
});

console.log(array1);

const array2 = number.map(function (value,index) {
    return value*2;
});

console.log(array2);

number.forEach(function (value,index) {
    console.log(value);
})
var arr = [1,2,4,4,3,3,1,5,3];

function res(arr) {
    var tmp = [];
    arr.sort().sort(function (a,b) {
        console.log(a,b);
        if(a === b && tmp.indexOf(a) === -1){
            tmp.push(a)
        }
    })
    return tmp
}
var result = res(arr);
console.log(result )