Get Transform X Value Ion-Slide-Box

I want to retrieve and watch transform X value in my controller from one slide of my ionic-slide-box when user slide.

I have try a lot of solutions like jQuery :

window.onload = function(){

var matrix = $('#fSlide').css('transform');
var values = matrix.match(/-?[\d\.]+/g);



 function getComputedTranslateX(obj)
     if(!window.getComputedStyle) return;
     var style = getComputedStyle(obj),
         transform = style.transform || style.webkitTransform || style.mozTransform;
     var mat = transform.match(/^matrix3d\((.+)\)$/);
     if(mat) return parseFloat(mat[1].split(', ')[13]);
    mat = transform.match(/^matrix\((.+)\)$/);
     return mat ? parseFloat(mat[1].split(', ')[5]) : 0;

But nothing work, I always have error like “TypeError: Cannot read property ‘style’ of null” …

I’m sure I use the wrong solution and I follow the wrong path …

Do you have an idea for me ? Thank you.