Add/Remove array object using key found in string array

Question

I'm trying to implement a function to select multiple items from one and add/remove to another using typescript.

        //data of the display list, each element has same value for text & value.
        private listA: any = {};  
        private listB: any = {};  

        //string array contains the list of name selected
        private selectA: string[] = [];  
        private selectB: string[] = [];

        private addClick: void {

            //remove all from listA that match name found in selectA
            //add to listB all name found in selectA
        }

How would I go about to implement this function? I already manage to get the data (listA & listB) to populate my list so that is not an issue, my issue is to prepare the data properly for it.

I'm new to typescript & javascript so the syntax is what giving problem now. I tried to work with Object.assign(), delete and couple of other functions I found but no luck so far.

Can you update the example with some data in the lists so we can get a better picture of what's going on. listA and listB are arrays? They're typed as objects right now. — Tom Faltesek
– Tom Faltesek, Commented Jul 3, 2019 at 18:02
The listA & listB are list of object that was parsed from a http post response. to be more percise, it contains two string properties calls text & value. listA = response.data.map((val: any) => { const el: any = {}; el.text = val.name; el.value = val.name; return el; }); — Fylix
– Fylix, Commented Jul 3, 2019 at 18:16
FYI - You can make your original assignment of listA more concise if you want. this.listA = response.data.map(val => ({ text: val.name, value: val.name })); — Tom Faltesek
– Tom Faltesek, Commented Jul 3, 2019 at 18:25

Tom Faltesek · Accepted Answer · 2019-07-03 18:18:52Z

1

Is this what you're looking for?

  // data of the display list, each element has same value for text & value.
  private listA: any[] = [];
  private listB: any[] = [];

  // string array contains the list of name selected
  private selectA: string[] = [];
  private selectB: string[] = [];

  private addClick(): void {
    // Get items from listA that match selectA.
    const matching = this.listA.filter(x => this.selectA.includes(x.value));

    // Filter listA to only include items that are not a match from selectA.
    this.listA = this.listA.filter(x => !this.selectA.includes(x.value));

    // Add matching items from listA to listB.
    this.listB.push(matching);
  }

this.listB.push(matching) appends the elements to the end of the array. You can also use this.listB.unshift(matching) to prepend them to the start.

answered Jul 3, 2019 at 18:18

Tom Faltesek

2,8182 gold badges21 silver badges31 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Fylix Over a year ago

Thanks t8tortolover, this is exactly what I need, I'll try it out with the unshift as well ...

M.Elkady · Accepted Answer · 2019-07-03 18:23:32Z

I'm not sure that I understand 100% your problem but I tried this and it seems to work check it and we can modify it till reach what you need

class Test {     //data of the display list, each element has same value for text & value.
    private listA: any = {a:'a','b':'b'};
    private listB: any = {};

//string array contains the list of name selected
    private selectA: string[] = ['a','b'];
    private selectB: string[] = [];

    public addClick(): void {
        this.selectA.forEach((item) => {
            if (this.listA[item]) {
                this.listB[item] = item;
                delete this.listA[item];
            }
        })
    }

    public showResult(){
        console.log('ListA',this.listA)
        console.log('SelectA',this.selectA)
        console.log('ListB',this.listB)
    }

    //remove all from listA that match name found in selectA
    //add to listB all name found in selectA
}

Then we can run this

let test = new Test();

test.showResult();
test.addClick();
test.showResult();

the Result will be as expected

ListA { a: 'a', b: 'b' }
SelectA [ 'a', 'b' ]
ListB {}
ListA {}
SelectA [ 'a', 'b' ]
ListB { a: 'a', b: 'b' }

John Montgomery · Accepted Answer · 2019-07-03 18:22:56Z

0

Steps

Iterate through the selected items from selectA
Get the index of each item in listA
Use splice(param1, param2) method to delete one item at a time from the list
Add the item in selectB list as well as listB

Note:- splice() method will mutate the original list ; If you don't want to mutate the list, you can use filter() method

edited Jul 3, 2019 at 18:22

John Montgomery

7,10610 gold badges58 silver badges73 bronze badges

answered Jul 3, 2019 at 18:10

Arvind sharma

524 bronze badges

Collectives™ on Stack Overflow

Add/Remove array object using key found in string array

3 Answers 3

1 Comment

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

1 Comment

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related