Author: John Au-Yeung

Web developer specializing in React, Vue, and front end development.

Categories
React Answers

How to select all text in input with React when it focused?

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Sometimes, we want to select all text in input with React when it focused.

In this article, we’ll look at how to select all text in input with React when it focused.

How to select all text in input with React when it focused?

To select all text in input with React when it focused, we can call select on the input element to select the input value when the element is in focus.

For instance, we write

const Comp = () => {
  //...
  const inputEl = useRef(null);

  const handleFocus = () => {
    inputEl.current.select();
  };

  <input
    type="number"
    value={quantity}
    ref={inputEl}
    onChange={(e) => setQuantityHandler(e.target.value)}
    onFocus={handleFocus}
  />;
};

to assign the inputEl ref to the input.

Then we set the onFocus prop to the handleFocus function, which runs when we focus on the input.

In handleFocus, we call inputEl.current.select to select all the input value text in the input box.

Conclusion

To select all text in input with React when it focused, we can call select on the input element to select the input value when the element is in focus.

Categories
JavaScript Answers

How to get the containing form of an input with JavaScript?

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Sometimes, we want to get the containing form of an input with JavaScript.

In this article, we’ll look at how to get the containing form of an input with JavaScript.

How to get the containing form of an input with JavaScript?

To get the containing form of an input with JavaScript, we can use the form property.

For instance, we write

const form = inputEl.form;

to get the form element that inputEl is in with the inputEl.form property.

Conclusion

To get the containing form of an input with JavaScript, we can use the form property.

Categories
React Answers

How to test a className with the Jest and React testing library?

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Sometimes, we want to test a className with the Jest and React testing library.

In this article, we’ll look at how to test a className with the Jest and React testing library.

How to test a className with the Jest and React testing library?

To test a className with the Jest and React testing library, we can check if any element with the given class name exists with getElementsByClassName.

For instance, we write

it("Renders with a className equal to the variant", () => {
  const { container } = render(<Button variant="default" />);
  expect(container.getElementsByClassName("default").length).toBe(1);
});

to call render to render the Button component.

Then we get the container element and call getElementsByClassName with the class name to check if any element with class name default exists in the container element.

We check if the length is bigger than 0 to see if any element with the class name exists.

Conclusion

To test a className with the Jest and React testing library, we can check if any element with the given class name exists with getElementsByClassName.

Categories
Vue Answers

How to fire an event when v-model changes with Vue.js?

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Sometimes, we want to fire an event when v-model changes with Vue.js.

In this article, we’ll look at how to fire an event when v-model changes with Vue.js.

How to fire an event when v-model changes with Vue.js?

To fire an event when v-model changes with Vue.js, we an listen for the change event.

For instance, we write

<template>
  <input
    type="radio"
    name="optionsRadios"
    id="optionsRadios2"
    value=""
    v-model="srStatus"
    @change="foo"
  />
</template>

to listen for the change event with @change.

If the event is emitted, then we run the foo method.

Conclusion

To fire an event when v-model changes with Vue.js, we an listen for the change event.

Categories
JavaScript Answers

How to filter array by multiple conditions with JavaScript?

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Sometimes, we want to filter array by multiple conditions with JavaScript.

In this article, we’ll look at how to filter array by multiple conditions with JavaScript.

How to filter array by multiple conditions with JavaScript?

To filter array by multiple conditions with JavaScript, we can use the array filter method.

For instance, we write

const filter = {
  address: "England",
  name: "Mark",
};
const users = [
  {
    name: "John",
    email: "johnson@mail.com",
    age: 25,
    address: "USA",
  },
  {
    name: "Tom",
    email: "tom@mail.com",
    age: 35,
    address: "England",
  },
  {
    name: "Mark",
    email: "mark@mail.com",
    age: 28,
    address: "England",
  },
];

const filteredUsers = users.filter((item) => {
  for (const key of Object.keys(filter)) {
    if (item[key] === undefined || item[key] !== filter[key]) {
      return false;
    }
  }
  return true;
});

console.log(users);

to call users.filter with a callback.

In the callback, we loop through the filter object’s keys we get from Object.keys.

In the loop, we check the value of each filter value to see if they’re what we’re looking for.

If they’re not, we return false.

Otherwise, we return true to include it in the filtered array returned.

Conclusion

To filter array by multiple conditions with JavaScript, we can use the array filter method.