jquery can only input numbers

jQuery can only input numbers - a brief analysis of jQuery digital verification

In recent years, front-end development has become the main direction of network application development. It is constantly developing and innovating, and various frameworks and tools emerge in endlessly. Among them, jQuery, as one of the famous JavaScript frameworks, is widely favored by front-end developers. The operation of jQuery is easy to learn and has good compatibility, which greatly improves the efficiency of front-end development. In the application process of jQuery, digital verification is a very common and important application scenario.

This article will discuss jQuery digital verification from the following aspects: the meaning of digital verification, implementation methods of digital verification, techniques to avoid digital verification errors, optimizing the performance of digital verification code, etc.

1. The meaning of digital verification

Number verification refers to the behavior of checking whether the input or output content is a number. It is often used in form input verification, data type verification and other scenarios to avoid user input Illegal characters cause system errors and improve system security and stability. The implementation methods of digital verification are very diverse, among which the jQuery library provides some very simple but practical methods and techniques, providing convenience and convenience to front-end developers.

2. Implementation method of digital verification

1. Detection implementation method

There are two main detection methods provided by the jQuery library.

(1)$.isNumeric() method

$.isNumeric() is used to detect whether a string is a number. It will return a Boolean type (true/false) result. If passed If the input parameter is a number, a string number, or a string containing numbers, it returns true, otherwise it returns false.

Syntax: $.isNumeric(value)

Example:

console.log($.isNumeric('1234')); //true
console. log($.isNumeric('23.4')); //true
console.log($.isNumeric('-123')); //true
console.log($.isNumeric('') ); //false
console.log($.isNumeric('abc')); //false

(2) isNaN() method

isNaN() method can also be used Used to check whether a variable is a number. It is more comprehensive than $.isNumeric(). It can determine NaN (Not a Number) type values ​​and can also detect string types.

Syntax: isNaN(value)

Example:

console.log(isNaN(1234)); //false
console.log(isNaN('23.4 ')); //false
console.log(isNaN('-123')); //false
console.log(isNaN('')); //false
console.log( isNaN('abc')); //true

2. Restrict input method

(1) Restrict input of non-numeric keys

Non-numeric keys include letters, symbols, etc. , jQuery's method can help us quickly achieve this requirement.

Syntax:

$('input').keypress(function(event) {

var keyCode = event.which;
if (keyCode < 48 || keyCode > 57) { //48-57是数字键的范围
    return false;
}

});

(2) Limit input of decimal point

If you want to limit the input of decimal points, you can make corresponding modifications based on the above, that is, increase the restrictions on decimal points.

Grammar:

$('input').keypress(function(event) {

var keyCode = event.which;
if ((keyCode < 48 || keyCode > 57) && keyCode != 46) { //添加小数点的条件
    return false;
}

});

3. Error prompt method

(1) Display error message

When the user enters illegal characters, we need to give an error message to tell the user that they have entered information in the wrong format. In the jQuery library, we can use the $.tipslayer() method to achieve this requirement, which can overlay a transparent image on the input box and display the corresponding prompt information.

Syntax:

$('#input-id').tipslayer("The content you entered is not a numeric type, please re-enter!", {

closeTime: 3000,//提示关闭时间（毫秒）
closeIcon: true,//是否显示关闭按钮
closeText: '[关闭]',//关闭按钮显示文本
layerStyle: {color:'#fff',position:'absolute',padding:'10px',background:'#f46'}

} );

(2) Hide error message

When the user re-enters content, the previously displayed error message needs to be hidden. jQuery provides the $.tipslayer.close() method, which can help us easily clear error prompts.

Syntax:

$.tipslayer.close();

3. Tips to avoid digital verification errors

In the process of implementing digital verification, We need to avoid errors in our own code, otherwise it will cause inconvenience to users and threaten the stability and security of the system. The following are some tips to avoid digital verification errors:

1. Make a preliminary judgment on the input data, such as judging whether the input value is empty, whether it meets the maximum and minimum value restrictions, etc.

2. When implementing digital verification, don’t forget to consider abnormal situations, such as users frantically entering numbers in the box, causing the server to crash.

3. Make reasonable use of jQuery integrated tools, such as using .validators() extension, $.tipslayer() method, etc.

4. Optimize code performance, reduce code redundancy, and reduce server pressure.

4. Optimize digital verification code performance

In order to improve code performance, we need to eliminate code redundancy and try to use jQuery integrated tools and methods to achieve digital verification.

The following are some tips for optimizing the performance of digital validation code:

1. Use jQuery's built-in validator - $.validator() extension.

In jQuery, use $.validator() to quickly write and implement form validation rules. Through it, we can implement a variety of different verification rules, such as required fields, number verification, email verification, URL format verification, etc. We only need to write a small amount of code to implement flexible and practical form validation rules, improving code reusability and readability.

2. Avoid using multi-level traversal to find DOM elements.

When we use multi-layer jQuery traversal to find DOM elements, it will consume a lot of CPU and memory resources, thereby reducing the performance of the code. Therefore, when writing jQuery number validation programs, we should use advanced selectors and cache DOM elements as much as possible to improve program execution efficiency.

3. Use CSS selectors instead of jQuery selectors.

The jQuery selector is very convenient and can quickly and accurately select the DOM structure we want, but it corresponds to expensive query operations. Therefore, when selecting elements, we should not abuse jQuery selectors and can use CSS selectors to reduce the burden of code.

4. Conclusion

This article mainly introduces the meaning and implementation methods of digital validation in jQuery, as well as techniques to avoid digital validation errors and methods to optimize code performance. It is hoped that readers can understand the basic concepts and implementation process of digital verification, thereby improving the practicality, readability, scalability and performance of the code. In the actual development process, based on the actual situation and combining some of the above-mentioned techniques, developers can achieve a more flexible, efficient, and secure digital verification function.

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