只要条件为真，如何添加特定数量的项目 JavaScript 数组

Question

I'm working on column selection from a table. I have a limit of 20 elements. I need to be able to select all items until the limit is passed.

Scenario: 18/20

• next column has 10 elements
• click on select whole column
• it should select only the first two elements

What I've tried:

const myArray = selectedColumn.some(() => itemsOnArray.length <= 20)
  ? selectedLaborer.map((laborer) => laborer)
  : [];

Answer 1

Can you provide more context to your question?

Personally when it comes to selections, i usually gives an id to the object i wish to select if they don't have one (An unique identifier) and store this value in an array as my selected objects.

Adding and removing values is quite easy then :

(This is typescript for more explicit reading, but doesnt change anything)

let selectedItems: string[] = [];
const MAX_ALLOWER_SELECTED = 20;

const selectItem = (itemId: string): void => {
    //You might want to check for duplicates before inserting
    if (selectedItems.length > MAX_ALLOWED_SELECTED)
        return;
    selectedItems.push(itemId);
}

const unselectItem = (itemId: string): void => {
    selectedItems = selectedItems.filter(id => itemId !== id);
}

const isItemSelected = (itemId: string): boolean => {
    return selectedItems.includes(itemId);
}