Check and remove null values in array

Question

I have an array that I am trying to check for null values. If there are any, I would like to remove them from the array. Here is my code and attempt.

this.existingSavings = [{
    value: null,
    sourceId: null,
    fund: null
}];

changeSavingsAmount(): void {
    for(let i = 0; i < this.existingSavings.length; i++) {
      if(this.existingSavings[i].value == null) {
        //not sure what to do here
      }
    }
}

<div *ngFor="let source of existingSavings; let i = index;" class="row">
   <div class="col-4">
     <div class="input-container">
        <label for="savings">Existing savings value</label>
        <input id="savings" [(ngModel)]="existingSavings[i].value" (blur)="changeSavingsAmount()" type="number"
          placeholder="R">
     </div>
   </div>
</div>

igg · Accepted Answer · 2020-01-25 14:39:27Z

1

If you only want to check the value property, you can use filter:

changeSavingsAmount(): void {
    this.existingSavings = this.existingSavings.filter(s => s.value != null);
}

Just be careful, as this is only checking the value property of each element in your array of object. The other two properties aren't checked, and neither is the element itself. You could do that with:

filter(s => s != null && s.value != null && s.sourceId != null && s.fund != null);

answered Jan 25, 2020 at 14:39

igg

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1 Comment

igg Over a year ago

A final note: in case the changes aren't picked up, try: this.existingSavings = [...this.existingSavings.filter(s => whatever you put here)]. This creates a new array and changes the reference of this.existingSavings and is more likely to be picked up by Angular's change detection.

Hasitha Amarathunga · Accepted Answer · 2020-01-25 14:58:15Z

1

You can also check it using forEach and ignore the null items as below.

changeSavingsAmount(): void {
    const existingSavings = [];
    this.existingSavings.forEach(exSave => {
      if (exSave[i].value != null) {
         existingSavings.push(exSave);
      }
    });
    this.existingSavings = existingSavings;
}

answered Jan 25, 2020 at 14:58

Hasitha Amarathunga

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Comments

kushal shah · Accepted Answer · 2020-01-25 14:50:21Z

0

solution using splice

in your ts file

existingSavings = [
    {
      value: null,
      sourceId: null,
      fund: null
    },
    {
      value: "f",
      sourceId: "dd",
      fund: null
    },
    {
      value: 't',
      sourceId: 'uu',
      fund: null
    }
  ];
  constructor() {
    var d = this.removeByAttr(this.existingSavings, "value", null);
    console.log(d);
  }
  removeByAttr(arr: any, attr: any, value: any) {
    var i = arr.length;
    while (i--) {
      if (
        arr[i] &&
        arr[i].hasOwnProperty(attr) &&
        (arguments.length > 2 && arr[i][attr] === value)
      ) {
        arr.splice(i, 1);
      }
    }
    return arr;
  }

answered Jan 25, 2020 at 14:50

kushal shah

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