[angularjs] How can I trigger the click event of another element in ng-click using angularjs?

I think you are over complicated things a bit. Do you really need to trigger a click on the input from your button ?

I suggest you just apply a proper style to your input and the ngFileSelect directive will do the rest and call your onFileSelect function whenever a file is submitted :

input.file {
    cursor: pointer;
    direction: ltr;
    font-size: 23px;
    margin: 0;
    opacity: 0;
    position: absolute;
    right: 0;
    top: 0;
    transform: translate(-300px, 0px) scale(4);
}