I have an array by the name students and a student object ```javascript let students = [] let student = { name: '', rollNumber: '', age: '', rank: '' } ``` # Following are immutable array Operations ### 1. adding an element to the array ```javascript students.concat([student]) ``` ### 2. Deleting an object based on index from array ```javascript var newStudentsArray = [...students.slice(0,index), ...students(index + 1)]; ``` ### 3. Deleting an object from the array based on some property ```javascript var newStudentArray = students.filter((student) => student.rank < 5) // will return a new array of all students whose rank is less than 5 ``` ###4. Updating a value of a particular object ```javascript var newStudentArray = students.map((student) => { if(someProperty !== student.key) return student return Object.assign({}, student, NEW_OBJECT) }) ``` or in Es6 ```javascript var newStudentArray = students.map((student) => { if(someProperty !== student.key) return student return {...student, NEW_OBJECT} }) ```