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There are two ways to use val in JavaScript: 1. Used to return the value attribute value of the first matching element, the syntax is "$(selector).val()"; 2. Used to set The value attribute value of all matching elements, the syntax is "$(selector).val(value)".
The operating environment of this tutorial: Windows 10 system, JavaScript version 1.8.5, Dell G3 computer.
The val() method returns or sets the value of the selected element.
The value of the element is set through the value attribute. This method is mostly used for input elements.
If this method does not set parameters, it returns the current value of the selected element.
Syntax
$(selector).val(value)
value Optional. Specifies the new content of the selected element.
Return the Value attribute
Return the value of the value attribute of the first matching element.
Syntax
$(selector).val()
Set the value of the Value attribute
$(selector).val(value)
value Set the value of the Value attribute.
Use a function to set the value of the Value attribute
$(selector).val(function(index,oldvalue))
function(index,oldvalue) specifies a function that returns the value to be set.
index - Optional. Accepts the index position of the selector.
oldvalue - Optional. Accepts the selector's current Value property.
The example is as follows:
<html>
<head>
<script type="text/javascript" src="/jquery/jquery.js"></script>
<script type="text/javascript">
$(document).ready(function(){
$("button").click(function(){
$("input:text").val("Bill Gates");
});
});
</script>
</head>
<body>
<p>Name: <input type="text" name="user" /></p>
<button>设置文本域的值</button>
</body>
</html>Output result:
javascript video tutorial, web front-end】
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