diff --git a/.gitignore b/.gitignore index d90ebd4..fa79e16 100644 --- a/.gitignore +++ b/.gitignore @@ -1,5 +1,5 @@ draft.md react-for-everyone.md component.md -12_Day_Forms + diff --git a/11_Day_Events/11_events.md b/11_Day_Events/11_events.md index d368239..d4f831f 100644 --- a/11_Day_Events/11_events.md +++ b/11_Day_Events/11_events.md @@ -14,7 +14,7 @@ -[<< Day 10](../10_React_Project_Folder_Structure/10_react_project_folder_structure.md) | [Day 12 >>]() +[<< Day 10](../10_React_Project_Folder_Structure/10_react_project_folder_structure.md) | [Day 12 >>](../12_Day_Forms/12_forms.md) ![30 Days of React banner](../images/30_days_of_react_banner_day_8.jpg) @@ -227,4 +227,4 @@ Implement the following using onMouseEnter event 🎉 CONGRATULATIONS ! 🎉 -[<< Day 10](../10_React_Project_Folder_Structure/10_react_project_folder_structure.md) | [Day 12 >>]() +[<< Day 10](../10_React_Project_Folder_Structure/10_react_project_folder_structure.md) | [Day 12 >>](../12_Day_Forms/12_forms.md) diff --git a/12_Day_Forms/12_forms.md b/12_Day_Forms/12_forms.md new file mode 100644 index 0000000..b010c5c --- /dev/null +++ b/12_Day_Forms/12_forms.md @@ -0,0 +1,879 @@ +
+

30 Days Of React: Forms

+ + + + + Twitter Follow + + +Author: +Asabeneh Yetayeh
+ October, 2020 + + +
+ +[<< Day 11](../11_Day_Events/11_events.md) | [Day 13 >>]() + +![30 Days of React banner](../images/30_days_of_react_banner_day_12.jpg) + +- [Forms](#forms) + - [Getting data from input field](#getting-data-from-input-field) + - [Getting multiple input data from form](#getting-multiple-input-data-from-form) + - [Get data from different input field types](#get-data-from-different-input-field-types) + - [Form Validation](#form-validation) + - [What is validation?](#what-is-validation) + - [What is the purpose of validation](#what-is-the-purpose-of-validation) + - [Validation Types](#validation-types) +- [Exercises](#exercises) + - [Exercises: Level 1](#exercises-level-1) + - [Exercises: Level 2](#exercises-level-2) + - [Exercises: Level 3](#exercises-level-3) + +# Forms + +Form is used to collect data from user. Once in a while we use form to fill our information on a paper or on a website. Either to sign up, sign in or to apply for a job we fill different form fields to submit data to remote database. We encounter different form fields when we fill a form such as simple text, email, password, telephone, date, checkbox, radio button, option selection and text area field. Currently, HTML5 has provide quite a lot of field types. You may have + +```html + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +``` + +Another HTML fields to get data from form are textarea and options. + +```html + + + +``` + +Now, you know most of fields we need to get data from a form. Let's start with an input of type text field. In the previous day, we saw different types of events and today we will focus on more of _onChange_ event type which triggers whenever an input field data changes. Input field has by default a memory to store input data but in this section we control that using state and we implement a controlled input. Today we will implement a controlled input. We will cover uncontrolled input in a separate section. + +## Getting data from input field + +So far we did not get any data from input field. Now, it is time to learn how to get data from an input field. We need on input field, event listener (onChange) and state to get data from a controlled input. See the example below. The h1 element below the input tag display what we write on the input. Check live [demo](https://codepen.io/Asabeneh/full/OJVpyqm). + +The input element has many attributes such as value, name, id, placeholder, type and event handler. In addition, we can link a label and an input field using an id of input field and htmlFor of the label.If label and input are linked it will focus the input when we click on label. Look at the example give below. + +```js +class App extends React.Component { + // declaring state + // initial state + state = { + firstName: '', + } + handleChange = (e) => { + const value = e.target.value + this.setState({ firstName: value }) + } + + render() { + // accessing the state value and this value will injected to the input in the value attribute + const firstName = this.state.firstName + return ( +
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+ ) + } +} +``` + +We usually use form to handle use information. Let us move to form section and make use the form element. + +## Getting multiple input data from form + +In this section we will develop a small form which collect user information. Our user is a student. We use a parent form element and certain number of input elements to collect user information. In addition to that we will have event listener for the form (onSubmit) and for the inputs (onChange). See the following example try to see the commonts too. You can also check the live [demo](https://codepen.io/Asabeneh/full/eYNvJda). + +```js +class App extends React.Component { + // declaring state + state = { + firstName: '', + lastName: '', + country: '', + title: '', + } + handleChange = (e) => { + /* + // we can get the name and value like this but we can also destructure it from e.target + const name = e.target.name + const value = e.target.value + */ + const { name, value } = e.target + // [variablename] this we can make a value stored in a certain variable could be a key for an object, in this case a key for the state + this.setState({ [name]: value }) + } + handleSubmit = (e) => { + // stops the default behavior of form element specifically refreshing of page + e.preventDefault() + console.log(this.state) + } + + render() { + // accessing the state value by destrutcturing the state + const { firstName, lastName, title, country } = this.state + return ( +
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+ ) + } +} +``` + +The above form handles only text types but can handle different input field types. Let's do another form which handle all the different input field types. + +## Get data from different input field types + +```js +// index.js +import React, { Component } from 'react' +import ReactDOM from 'react-dom' + +const options = [ + { + value: '', + label: '-- Select Country--', + }, + { + value: 'Finland', + label: 'Finland', + }, + { + value: 'Sweden', + label: 'Sweden', + }, + { + value: 'Norway', + label: 'Norway', + }, + { + value: 'Denmark', + label: 'Denmark', + }, +] + +// mapping the options to list(array) of JSX options + +const selectOptions = options.map(({ value, label }) => ( + +)) + +class App extends React.Component { + // declaring state + state = { + firstName: '', + lastName: '', + email: '', + country: '', + tel: '', + dateOfBirth: '', + favoriteColor: '', + weight: '', + gender: '', + file: '', + bio: '', + skills: { + html: false, + css: false, + javascript: false, + }, + } + handleChange = (e) => { + /* + // we can get the name and value like this but we can also destructure it from e.target + const name = e.target.name + const value = e.target.value + */ + const { name, value, type, checked } = e.target + // [variablename] this we can make a value stored in a certain variable could be a key for an object, in this case a key for the state + + if (type === 'checkbox') { + this.setState({ + skills: { ...this.state.skills, [name]: checked }, + }) + } else if (type === 'file') { + console.log(type, 'cehck here') + this.setState({ [name]: e.target.files[0] }) + } else { + this.setState({ [name]: value }) + } + } + handleSubmit = (e) => { + // stops the default behavior of form element specifically refreshing of page + e.preventDefault() + e.preventDefault() + const { + firstName, + lastName, + email, + country, + gender, + bio, + file, + skills, + } = this.state + + const formattedSkills = [] + for (const key in skills) { + console.log(key) + if (skills[key]) { + formattedSkills.push(key.toUpperCase()) + } + } + const data = { + firstName, + lastName, + email, + country, + gender, + bio, + file, + skills: formattedSkills, + } + console.log(data) + } + + render() { + // accessing the state value by destrutcturing the state + const { firstName, lastName, title, country } = this.state + return ( +
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