Replaced if-then-else. Just for fun...js

// Before

if ( self.data('branches') ) {
    checked_stack.push( this );
} else {
    var len = checked_stack.length;

    if ( this.checked === true ) {
        checked_stack.push( this );

        if ( checked_stack.length > max_selected ) {
            checked_stack.shift().checked = false;
        }

    } else {
        var arr = [];

        while ( len-- ) {

            if ( this.id !== checked_stack[len]['id'] ) {
                arr.push(checked_stack[len]);
            }

        }

        checked_stack = arr.reverse();
    }
}



// After

(self.data('branches') 
    && (
        checked_stack.push(this)
    )
) || 
(self.data('branches') 
    || (
        (this.checked === true
            && (
                checked_stack.push(this),
                (checked_stack.length > max_selected 
                    && (
                        checked_stack.shift().checked = false
                    )
                )
            )
        ) || 
        (this.checked === true 
            || (
                checked_stack = (function (len) {
                    var arr = [];
                    while ( len-- ) {
                        this.id !== checked_stack[len]['id'] && arr.push(checked_stack[len]);
                    } 
                    return arr;
                } (checked_stack.length) ).reverse()
            )
        )
        
    )
);