How to loop out multiple edit boxes in javascript

With the continuous development of web applications, more and more applications require users to enter multiple form data on one page. These form data may include text boxes, drop-down boxes, check boxes, etc. Front-end developers need to use javascript to handle form data, and need to be able to loop out multiple edit boxes to handle multiple form data.

There are two main ways to loop out multiple edit boxes in javascript: using a for loop and using a while loop. We will cover both methods one by one.

Method 1: Use for loop

Use for loop to traverse arrays and array-like objects. An array-like object refers to an object with a length property and some numeric properties, such as NodeList and HTMLCollection. The following sample code demonstrates how to use a for loop to traverse a NodeList containing multiple edit boxes:

var textareas = document.querySelectorAll('textarea'); // 获取所有textarea元素
for (var i = 0; i < textareas.length; i++) {
  textareas[i].value = '这是第' + (i+1) + '个编辑框'; // 设置编辑框的值
}

In the above code, we first use the querySelectorAll method to obtain all textarea elements, and then use a for loop to traverse these element. In the loop, we can operate on each edit box, such as setting its value attribute.

Method 2: Use while loop

Use while loop to traverse a list or collection, such as an array or a linked list. The following sample code demonstrates how to use a while loop to traverse an array containing multiple edit boxes:

var textareas = document.getElementsByTagName('textarea'); // 获取所有textarea元素
var i = textareas.length; // 初始化计数器
while (i--) {
  textareas[i].value = '这是第' + (i+1) + '个编辑框'; // 设置编辑框的值
}

In the above code, we first use the getElementsByTagName method to get all textarea elements, and then use a while loop to traverse these element. In the loop, we can operate on each edit box, such as setting its value attribute.

It should be noted that when using a while loop to process array-like objects, we need to use a counter to traverse the array. Since the index of the array starts from 0 and the value of the length property starts from 1, we need to initialize the counter to the length of the array minus 1.

Summary

This article introduces two methods of javascript looping out multiple edit boxes: using a for loop and using a while loop. These two methods are suitable for different types of collections, and front-end developers can choose the method that suits them according to the specific situation. At the same time, no matter which method is used, we can operate on each edit box and use loops to traverse multiple form data.

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