The requested behaviour is already implemented in angular material as documented here: Angular Material Input Autosize. This is especially useful if you are using angular material anyways.

Just use cdkTextareaAutosize as in the example:

<textarea cdkTextareaAutosize></textarea>

you can do like this without using the package. its simple

in controller like below

autogrow(){
  let  textArea = document.getElementById("textarea")       
  textArea.style.overflow = 'hidden';
  textArea.style.height = '0px';
  textArea.style.height = textArea.scrollHeight + 'px';
}

and in html like below

<textarea id="textarea" (keyup)="autogrow()" ></textarea>

Why you need plugins for this, it's as simple as :

<textarea (keyup)="autoGrowTextZone($event)"></textarea>

and

autoGrowTextZone(e) {
  e.target.style.height = "0px";
  e.target.style.height = (e.target.scrollHeight + 25)+"px";
}

Slightly modified answer for tanveer's answer would be to use @ViewChild

@ViewChild('textArea', { read: ElementRef }) textArea: ElementRef;

public autoGrow() {
 const textArea = this.textArea.nativeElement;
 textArea.style.overflow = 'hidden';
 textArea.style.height = '0px';
 textArea.style.height = textArea.scrollHeight + 'px';
}

And in the HTML it would be

<textarea (keyup)="autoGrow()" #textArea></textare>

The solution that worked for me on IE as well as in the other browser

// Usage example: <textarea autoresize></textarea>

import { ElementRef, HostListener, Directive} from '@angular/core';

@Directive({
    selector: 'textarea[autosize]'
})

export class Autosize {
 @HostListener('input',['$event.target'])
  onInput(textArea: HTMLTextAreaElement): void {
    this.adjust();
  }
  constructor(public element: ElementRef){
  }
  ngAfterContentChecked(): void{
    this.adjust();
  }
  adjust(): void{
    this.element.nativeElement.style.overflow = 'hidden';
    this.element.nativeElement.style.height = 'auto';
    this.element.nativeElement.style.height = this.element.nativeElement.scrollHeight + "px";
  }
}

Add the below code to the APp.Module.ts

@NgModule({
  declarations: [
    Autosize
  ]
})

Use the tag on the HTML

 <textarea autosize></textarea>

Simply

You can use as below:

<textarea [rows]="text.split('\n').length || 2">{{text}}</textarea>

or

create a function in ts :

  getHeight(content) {
    const v1 = Math.floor(content.length / 50);
    const v2 = content.split('\n').length;
    return Math.max(v1,v2)
  }

HTML:

<textarea [rows]="getHeight(text) || 2">{{text}}</textarea>

Create the directive from angular-cli and add following code

import { Directive, ElementRef, HostListener, Input } from '@angular/core';

@Directive({
selector: '[appAutoGrow]'
})
export class AutoGrowDirective {

constructor(public element: ElementRef) {
}
@Input() maximumHeight: number; // based on pixel
@Input() minHeight: number; // based on pixel
@HostListener('input', ['$event.target'])
@HostListener('cut', ['$event.target'])
@HostListener('paste', ['$event.target'])
@HostListener('change', ['$event.target'])

ngOnInit(): void {
    this.adjustCustom();
}

adjustCustom(): void {
    const element = this.element.nativeElement;
    element.style.height = this.minHeight + 'px';
    element.style.height = (element.scrollHeight) + 'px';
    if (element.scrollHeight <= this.maximumHeight) {

        element.style.overflowY = 'hidden'
        delete element.style.maxHeight
    } else {

        element.style.overflowY = 'scroll'
        element.style.maxHeight = this.maximumHeight + 'px';
    }

}
}

and use the directive as follows

<textarea autofocus [maximumHeight]="200" [minHeight]="43" appAutoGrow></textarea>

I know the topic is quite old but I just change tanveer's answer to enter maximum Height as well.

    import { Directive, ElementRef, OnInit, HostListener, Input } from '@angular/core';

@Directive({
  selector: '[appAutoResize]',

})
export class AutoResizeDirective implements OnInit {
  constructor(public element: ElementRef) {
  }
  @Input() maximumHeight: number; // based on pixel
  @HostListener('input', ['$event.target'])
  ngOnInit(): void {
    this.adjust();
  }

  adjust(): void {
    const ta = this.element.nativeElement;
    const maxHeghit = this.maximumHeight;
    ta.style.overflow = 'hidden';
    ta.style.height = 'auto';
    if (ta.scrollHeight <= maxHeghit) { // while current height is less than maximumHeight
      ta.style.height = ta.scrollHeight + 'px';
    } else { // greater than maximumHeight
      ta.style.height = maxHeghit + 'px';
      ta.style.overflow = 'auto';
    }
  }

}

So, you will have control on the style behavior.
I hope it can help.

Here is the implementation of autosize in a directive which you can reuse on any textarea in your project.

import { Directive, Input, HostBinding } from '@angular/core';

@Directive({
    selector: 'textarea[autosize]'
})

export class TextareaAutosizeDirective {

    private _ngModel: any;

    public get ngModel(): any {
        return this._ngModel;
    }

    @Input()
    public set ngModel(value: any) {
        if (this._ngModel !== value) {
            this._ngModel = value;
            this.resize();
        }
    }

    @HostBinding('rows')
    public rows: number;

    @Input()
    public minRows: number = 1;

    constructor() {}

    private resize() {
        this.rows = !this._ngModel ? this.minRows : this.ngModel.split('\n').length;
    }

}

You can use it in a following way:

<textarea autosize minRows="2" [(ngModel)]="property"></textarea>

By adding autosize textarea becomes automatically resized. You can also specify minimum number of rows which textarea has.