Method _addWatcher

src/AutoNumeric.js:1550–1582

* Add a watcher so that any external change to the AutoNumeric-managed element would be detected. * As soon as such change is detected, AutoNumeric then tries to `set()` the value so that it gets formatted and stored in the history. * //XXX For now, this only works when watching the `value

()

     * @private
     */
    _addWatcher() {
        // `getterSetter` can be undefined when a non-input element is used
        if (!AutoNumericHelper.isUndefined(this.getterSetter)) {
            const { set: setter, get: getter } = this.getterSetter;
            Object.defineProperty(this.domElement, this.attributeToWatch, {
                configurable: true, // This is needed in some rare cases
                get         : () => getter.call(this.domElement),
                set         : val => {
                    setter.call(this.domElement, val);
                    // Only `set()` the value if the modification comes from an external source
                    if (this.settings.watchExternalChanges && !this.internalModification) {
                        this.set(val);
                    }
                },
            });
        }

        //FIXME The code above fails for the `textContent` attribute since `this.getterSetter` is undefined when using `getOwnPropertyDescriptor()`
        /* //XXX The code below *almost* work for the textContent, but breaks some unit tests
        this.valueWatched = this.domElement[this.attributeToWatch];
        Object.defineProperty(this.domElement, this.attributeToWatch, {
            configurable: true, // This is needed in some rare cases
            get         : () => this.valueWatched,
            set         : val => {
                this.valueWatched = val;
                // Only `set()` the value if the modification comes from an external source
                if (this.settings.watchExternalChanges && !this.internalModification) {
                    this.set(val);
                }
            },
        });
        */
    }

    /**
     * Remove the watcher on the AutoNumeric-managed element