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  4. HTML attribute: max

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max attribute defines the maximum value that is acceptable and valid for the input containing the attribute. If the value of the element is greater than this, the element fails constraint validation . This value must be greater than or equal to the value of the min attribute. If the max attribute is present by is not specified or is invalid, no max value is applied. If the max attribute is valid and a non-empty value is greater than the maximum allowed by the max attribute, constraint validation will prevent form submission.

Valid for the numeric input types, including the date , month , week , time , datetime-local , number and range types, and both the <progress> and <meter> elements, the max attribute is a number that specifies the most positive value a form control to be considered valid.

If the value exceeds the max value allowed, the validityState.rangeOverflow will be true, and the the control will be matched by the :out-of-range and :invalid pseudo-classes.

句法

Syntax for max values by input type
Input type 句法 范例
date yyyy-mm-dd <input type="date" max="2019-12-25" step="1">
month yyyy-mm <input type="month" max="2019-12" step="12">
week yyyy-W## <input type="week" max="2019-W23" step="">
time hh:mm <input type="time" max="17:00" step="900">
datetime-local yyyy-mm-ddThh:mm <input type="datetime-local" min="2019-12-25T23:59">
number <number> <input type="number" min="0" step="5" max="100">
range <number> <input type="range" min="60" step="5" max="100">

注意： When the data entered by the user doesn't adhere to the maximum value set, the value is considered invalid in contraint validation and will match the :invalid and :out-of-range pseudo-classes.

见 Client-side validation and rangeOverflow 了解更多信息。

对于 <progress> element, the max attribute describes how much work the task indicated by the progress element requires. If present, must have a value greater than zero and be a valid floating point number. For the <meter> element, the max attribute defines the upper numeric bound of the measured range. This must be greater than the minimum value ( min attribute), if specified. In both cases, if omitted, the value defaults to 1.

Syntax for max values for other elements
Input type 句法 范例
<progress> <number> <progress id="file" max="100" value="70"> 70% </progress>
<meter> <number> <meter id="fuel" min="0" max="100" low="33" high="66" optimum="80" value="40"> at 40/100</meter>

可访问性关注

Provide instructions to help users understand how to complete the form and use individual form controls. Indicate any required and optional input, data formats, and other relevant information. When using the max attribute, ensure this maximum requirement is understood by the user. Providing instructions within the <label> may be sufficient. If providing instructions outside of labels, which allows more flexible positioning and design, consider using aria-labelledby or aria-describedby .

规范

规范 状态 注释
HTML 实时标准
The definition of 'max attribute' in that specification. 		实时标准
HTML5
The definition of 'max attribute' in that specification. 		推荐
HTML 实时标准
The definition of 'progress element' in that specification. 		实时标准
HTML5
The definition of 'progress element' in that specification. 		推荐
HTML 实时标准
The definition of 'meter element' in that specification. 		实时标准
HTML5
The definition of 'meter element' in that specification. 		推荐

浏览器兼容性

The compatibility table on this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request.

No compatibility data found. Please contribute data for "html.elements.attributes.max" (depth: 1) to the MDN 兼容性数据存储库 .

另请参阅

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