Javascript/Lodash 动态添加或删除数组元素

Question

let order = [
   { column1 : "asc" },
   { column2 : "desc" },
   { column3 : "asc" }
]

I need help implementing the following function:

function sorting(columnName) {
   // I'm losted
}

The business rule of the function is as follows:

1. Keep only objects with value "asc" or "desc" can exist in the array.
2. Columns must be unique.
3. If the column has a value of "asc", it must be changed to "desc".
4. If the column has the value "desc", the object must be removed from the array.
5. If the column does not exist, it must receive the value "asc" and be inserted at the END of the array.

This is the algorithm, but I can't implement it because of my lack of JS/Lodash skills.

I thank you all.

Note: I'm not asking for the implementation, but maybe a guide regarding the functions that could better solve the issue in native Javascript or using Lodash.

Answer 1

I wrote some code to inspire you. However it has a big catch : I changed the data structure used for 'order'. You will find out having the right data structure for the task is one of the most important things. Sometimes the first step of an algorithm is creating a data structure that makes it easier/faster to implement the desired algorithm. You probably are stuck with the order array and have to find a way to iterate it.

 // Columns must be unique. let order = { "column1": "asc", "column2": "desc", "column3": "asc" }; // Keep only objects with value "asc" or "desc" can exist in the array. function sorting(columnName) { // If the column does not exist, it must receive the value "asc" and be inserted at the END of the array. if (order[columnName] === undefined) { order[columnName] = 'asc'; } // If the column has a value of "asc", it must be changed to "desc". else if (order[columnName] === 'asc') { order[columnName] = 'desc'; } // If the column has the value "desc", the object must be removed from the array. else if (order[columnName] === 'desc') { delete order[columnName]; } } // Tests console.log(order); sorting('column4'); console.log(order); sorting('column1'); console.log(order); sorting('column1'); console.log(order);