I guess it will work in the same way as in normal CSS. You can use
text-align: center for it. In this case I added
div that includes a class
centrado to give more context and that is relevant but you can put any name.
<button class="button button-block button-positive" ng-click="facebookLogin()" style="width:300px;">
<i class="icon ion-social-facebook"></i>
Continuar con facebook
Seeing that with the comments the problem was the class
button-block I researched a bit about it and as it puts in the Ionic documentation when you indicate the class
button-block to a button it takes the property
display: block; , that is, it is considered as a block.
That's why with the property
text-align: center the button was not centering, because the property
text-align: center only affects elements
inline or elements
The button is a
inline by default, and under normal conditions it should be enough using
text-align: center in its container. However, as in this case we were telling him to behave like a block this property was not making any effect.
As you very well said, removing this property the button will be centered. Why? Because the button will return to its default state, in which it is considered as a
inline element and therefore if it will affect the property
text-align: center .