irisrad-ui/src/components/irisSelect/Select.js

UI elements developered for IRIS R&D Group Inc

let debounceTimeout;
let searchTerm = "";

let onListBlurred;
let onKeyDown;
let onLabelClicked;
let onListItemClicked;

export default class Select {
  constructor(element) {
    this.selectEle = element;
    this.optionObjects = getFormattedOptions(
      element.querySelector("ul").childNodes
    );

    this.customSelectContainer = element.querySelector(
      ".iris-custom-select-container"
    );

    this.customSelectLabel = element.querySelector(".iris-custom-select-label");

    this.optionList = element.querySelector(".iris-custom-select-list");
    this.registerEvents();
    setupCustomElement(this);
  }

  /**
   * get the selected default option
   */
  get selectedOption() {
    const target = this.optionObjects.find((option) => option.selected);
    if (target) {
      return target;
    } else {
      const firstOption = this.optionObjects[0];
      firstOption.selected = true;
      firstOption.element.classList.add("selected");
      if (this.selectEle.onChange) {
        this.selectEle.onChange(firstOption.value);
      }
      return firstOption;
    }
  }

  /**
   * get the index of the selected option
   */
  get selectedOptionIndex() {
    return this.optionObjects.indexOf(this.selectedOption);
  }

  setSelectedValue(value) {
    // find previously selected option;
    const prevSelectedOption = this.selectedOption;
    // set its selected state as false
    prevSelectedOption.selected = false;

    // remove selected css style from the option
    // this.optionList
    //   .querySelector(`[data-value="${prevSelectedOption.value}"]`)
    prevSelectedOption.element.classList.remove("selected");

    // find the reference of the selected option
    const newSelectedOption = this.optionObjects.find((option) => {
      return option.value === value;
    });
    // set its selected state as true
    newSelectedOption.selected = true;

    // set the label's innerText with the one of the selected option
    this.customSelectLabel.innerText = newSelectedOption.label;

    // add stelected css style on the selected option
    newSelectedOption.element.classList.add("selected");
    // scroll to the selected option if necessary
    newSelectedOption.element.scrollIntoView({ block: "center" });

    // call the onchange callback function which is passed to the original element (select)

    if (value !== prevSelectedOption.value && this?.selectEle?.onChange) {
      this.selectEle.onChange(value);
    }
  }

  registerEvents() {
    onListBlurred = handlOnListBlurred.bind(this);
    onKeyDown = handlOnKeyDown.bind(this);
    onLabelClicked = handleOnLabelClicked.bind(this);
    onListItemClicked = handleListItemClick.bind(this);

    this.optionObjects.forEach((option) => {
      option.element.addEventListener("click", onListItemClicked);
    });

    this.customSelectContainer.addEventListener("blur", onListBlurred);
    this.customSelectContainer.addEventListener("keydown", onKeyDown);
    this.customSelectContainer.addEventListener("click", onLabelClicked);
  }

  unregisterListeners() {
    this.customSelectContainer.removeEventListener("blur", onListBlurred);
    this.customSelectContainer.removeEventListener("keydown", onKeyDown);
    this.customSelectContainer.removeEventListener("click", onLabelClicked);

    this.optionObjects.forEach((option) => {
      option.element.removeEventListener("click", onListItemClicked);
    });
  }
}

function handlOnKeyDown(event) {
  switch (event.code) {
    case "Space":
      this.optionList.classList.toggle("show");
      break;
    case "ArrowUp": {
      const prevOption = this.optionObjects[this.selectedOptionIndex - 1];
      if (prevOption) {
        this.setSelectedValue(prevOption.value);
      }
      break;
    }
    case "ArrowDown": {
      const nextOption = this.optionObjects[this.selectedOptionIndex + 1];
      if (nextOption) {
        this.setSelectedValue(nextOption.value);
      }
      break;
    }
    case "Enter":
      this.optionList.classList.toggle("show");
      break;
    case "Escape":
      this.optionList.classList.remove("show");
      break;
    default: {
      clearTimeout(debounceTimeout);
      searchTerm += event.key;
      debounceTimeout = setTimeout(() => {
        searchTerm = "";
      }, 500);

      const searchedOption = this.optionObjects.find((option) => {
        return option.label.toLowerCase().startsWith(searchTerm);
      });
      if (searchedOption) {
        this.setSelectedValue(searchedOption.value);
      }
    }
  }
}

function handlOnListBlurred() {
  this.optionList.classList.remove("show");
}
// click listener for each list option
function handleListItemClick(event) {
  event.stopPropagation();
  const optionValue = event.target.getAttribute("value");
  this.setSelectedValue(optionValue);
  this.optionList.classList.remove("show");
}

function handleOnLabelClicked() {
  if (!this.optionList.classList.contains("show")) {
    this.optionList.classList.toggle("show");
  }
  this.selectedOption.element.scrollIntoView({ block: "center" });
}

function setupCustomElement(select) {
  const customSelectContainer = select.customSelectContainer;
  const customSelectLabel = select.customSelectLabel;
  customSelectContainer.tabIndex = 0;
  customSelectLabel.innerText = select.selectedOption.label;
}

/**
 * @description given a nodelist of html default options, generate an array of objects which containes the following properties:
 * value: option's value of property [value]
 * label: the html innerText of the option element
 * selected: the boolean value of property [selected]
 * element: the option node itself
 *
 * @param {Array} optionElements an array of default html option elements (NodeList)
 * @returns an array of objecs, in the shape of {value: string, label: string, selected: boolean, element: the_option_node_itself}
 */
function getFormattedOptions(optionElements) {
  return [...optionElements].map((optionElement) => {
    optionElement.classList.add("iris-custom-select-option");
    if (optionElement.selected) {
      optionElement.classList.add("selected");
    }
    return {
      value: optionElement.getAttribute("value"),
      label: optionElement.innerText,
      selected: optionElement.selected,
      element: optionElement,
    };
  });
}