Hide and Show textbox when ion-select is change

I want to hide and show the textbox when the ion-select(combobox) is change

For example I have : 1 and 2 in ion-select
If i choose 1 the textbox will hide and if i choose 2 the textbox will appear

Here is my current code:

.ts

  onChange(membership){
  	   if (this.membership = '1'){
  	   this.value = 1; }
           else if (this.membership = '2'){
          this.value = ""; }
  }

HTML

<ion-list>
  <ion-item>
    <ion-label>Register as</ion-label>
    <ion-select [(ngModel)]="membership" (ionChange)="onChange(membership)">
      <ion-option value="1">member</ion-option>
     <ion-option value="2">nonmember</ion-option>
    </ion-select>
  </ion-item>
</ion-list>

this is the textbox that i want to hide

   <ion-item [hidden]="!value">
    <ion-label floating>Email Address</ion-label>
    <ion-input type="text" name="email"  ></ion-input>
  </ion-item>

When I’m opening the application the textbox is hiding and when i select from the combobox the textbox is showing but when I select the other item in the combobox its not hiding anymore.

Try this onChange(membership){ if (this.membership == '1') { this.value = 1; } else if (this.membership == '2'){ this.value = 0; } }