How to test if child component was clicked?

I need to test (not trigger) if a click is done inside or outside a child component, including the DOM elements from this child and the sub-children.

I was using this code inside the child component with a ref on the main <div>, it works well, but I need the test to be executed from the parent element and it doesn’t work this way :

  mounted() {
    window.addEventListener('click', this.handleClickOutside);
    }

methods: {
    handleClickOutside(event) {
            let targetElement = this.$refs.element;
            if (!targetElement.contains(event.target)) {
                console.log("click")
            }
        },
}

When trying to add the same code in the parent with a ref on the component, I get the error : targetElement.contains is not a function.
I guess this is because the Vue component doesn’t implement the contains method, so is there a way to achieve the same test from the parent side ?