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How to create an element from a string in JavaScript?

王林
王林forward
2023-08-27 18:21:031824browse

如何在 JavaScript 中从字符串创建元素？

In this tutorial, we will look at the various ways to create elements from strings in JavaScript. Creating elements from strings can be very useful if we have to generate elements dynamically to make the website interactive. An example is like in to-do list app where we add, delete and edit to-do items.

createElement() method

We create JavaScript items using the createElement() method. To create a specific element, we pass the item name as a string into the createElement() method.

createElement(tagName) The function has one parameter as the name of the tag that will be created using this method. Here tagName is the parameter name, which will be in string form. Note that only one element is created from a string.

grammar

document.createElement("tagName")

In the position of tagName, we pass the tag name, such as p (paragraph), h1 (title 1), img (picture). createElement will make tagName lowercase so you don't have to worry about case.

step

  • Step 1 - Create a string using element values ​​like h3 and p

  • Step 2 - Pass the string as a parameter to the createElement() method. Assign a value to a variable. This will create the elements we need.

  • Step 3 - After creating the elements, we assign the required text to both elements using the innerText attribute.

  • STEP 4 - After all, append we use append() or appendChild() method to append the created element to the web page so that it is visible to the web user.

Let's create a title and a paragraph from strings. 

let string1="h3"
let string2="p"
let element1=document.createElement(string1)
let element2=document.createElement(string2)

So you have to understand how we create an element, but creating an element does not help in displaying that element to the user because it is not part of the DOM, instead we have to make it a part of the DOM by attaching it to the web page.

Therefore, we use some methods such as append() and appendChild().

Example

Use the append() method to append the created element.

In the example below, we create two elements h3 and p using the document createElement() method. Then assign some text to these elements and use the append() method to append the elements to the DOM. Finally, the element is displayed using the innerHTML attribute. 

<html>
<head>
   <title>Creating elements from string in JavaScriptnhi</title>
</head>
<body>
   <script>
      let string1="h3"
      let string2="p"
      let element1=document.createElement(string1)
      let element2=document.createElement(string2)
      element1.innerText="An h3 element using string"
      element2.innerText="A paragraph element using string"
      document.body.append(element1)
      document.body.append(element2)
   </script>
</body>
</html>

Example

Use the appendChild() method to append the created element.

In the example below, we create two elements h3 and p using the document createElement() method. Then assign some text to these elements and append the elements to the DOM using the appendChild() method. Finally, display the element using the innerHTML

attribute 
<html>
<head>
   <title>Creating elements from string in JavaScript </title>
</head>
<body>
   <script>
      let string1="h3"
      let string2="p"
      let element1=document.createElement(string1)
      let element2=document.createElement(string2)
      element1.innerText="An h3 element using string"
      element2.innerText="A paragraph element using string"
      document.body.appendChild(element1)
      document.body.appendChild(element2)
   </script>
</body>
</html>

Now you may be thinking, the output of the above program is the same, so what makes the two programs different?

Well, yes, both are used to append nodes to HTML document, but in case, append() method will return the appended node, but appendChildI() method will not return any content.

Using the append() method we can append multiple elements at a time, but in the appendChild() method we can only append one element at a time.

like

document.body.append(element1, element2)

This will do the same job as 

document.body.append(element1)
document.body.append(element2)

Using the append() method DOMString and DOMNodes can both be appended to the parent element, but in this case only appendChild()method DOMNodes can be attached to parent elements.

So, these are some of the ways we can create elements from strings.

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JavaScript html 字符串 append dom innerHTML
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