编辑代码

//let arr = [{name:'小张', age: '18', sex: 'male', area: 'suzhou'},{name:'小明', age: '23', sex: 'female', area: 'shanghai'},{name:'小红', age: '21', sex: 'female', area: 'shanghai'},{name:'小军', age: '32', sex: 'male', area: 'beijing'}]

//console.log(arr);

let arr = [1,2,3,4]; 

let newArr1 = arr.push(5, 6, 7, 8, 9, 'last');
console.log(arr);
console.log(newArr1);

// let newArr2 = arr.pop();
// console.log(arr);
// console.log(newArr2);

// let newArr1 = arr.unshift('first', 0.8, 0.9);
// console.log(arr);
// console.log(newArr1);

// let newArr2 = arr.shift();
// console.log(arr);
// console.log(newArr2);

arr.splice(3,5)
console.log(arr);
arr.splice(3,0,'新元素1','新元素2','新元素3');
console.log(arr);
arr.splice(1,2,'新元素');
console.log(arr);


console.log(arr.join(';'));