jquery input box loses focus after input

With the continuous development of front-end technology, jquery has become an indispensable tool in many web development. Among them, the use of input boxes is inevitable. After the user input is completed, how to trigger related operations to make the user's operations more convenient has become a problem that front-end developers need to consider. This article will introduce how to use jquery to realize that the input box loses focus after input.

1. Requirements

After the input in the form input box is completed, form submission or related operations are triggered to improve the user experience. At the same time, after the input box loses focus, certain verification and prompts can be performed, such as verifying whether the email format is correct, etc.

2. Implementation process

1. Binding events

First, we need to bind the event of the input box, you can use bind() or on() in jquery method to bind. In this article, we use the on() method.

$(function(){
    $("#input-id").on('blur',function(){
        //触发相关操作，例如表单提交、验证等
    });
})

2. Get the value of the input box

In the event function, how to get the value of the input box? We can use the val() method to get the value of the input box. On this basis, we can perform related operations, such as verification.

$(function(){
    $("#input-id").on('blur',function(){
        var inputValue = $(this).val();
        if(inputValue === ""){
            alert("您还未输入任何值！");
        }else{
            //触发相关操作，例如表单提交、验证等
        }
    });
})

3. Verify the value of the input box

After obtaining the value of the input box, we need to perform certain verification on the value of the input box. For example, verify that the email is formatted correctly. Based on this, we can use regular expressions to verify.

$(function(){
    $("#input-id").on('blur',function(){
        var inputValue = $(this).val();
        if(inputValue === ""){
            alert("您还未输入任何值！");
        }else{
            //验证邮箱格式是否正确
            var regExp = /^[a-zA-Z0-9_-]+@[a-zA-Z0-9_-]+(.[a-zA-Z0-9_-]+)+$/;
            if(regExp.test(inputValue)){
                //触发相关操作，例如表单提交、验证等
            }else{
                alert("请输入正确的邮箱格式！");
            }   
        }
    });
})

4. Use the debounce function

In actual development, we often encounter the problem of frequently triggering input box events. At this time, using the debounce function can effectively avoid this situation. The function of the debounce function is to trigger the same event multiple times and execute it only once within a certain period of time, thereby reducing the number of executions of the event.

function debounce(fn,delay){
    var timer = null;
    return function(){
        var context = this;
        var args = arguments;
        clearTimeout(timer);
        timer = setTimeout(function(){
            fn.apply(context,args);
        },delay);
    }
}

When using the debounce function, we only need to make certain modifications to the event function to achieve the debounce function.

$(function(){
    var fn = debounce(function(){
        var inputValue = $("#input-id").val();
        if(inputValue === ""){
            alert("您还未输入任何值！");
        }else{
            //验证邮箱格式是否正确
            var regExp = /^[a-zA-Z0-9_-]+@[a-zA-Z0-9_-]+(.[a-zA-Z0-9_-]+)+$/;
            if(regExp.test(inputValue)){
                //触发相关操作，例如表单提交、验证等
            }else{
                alert("请输入正确的邮箱格式！");
            }
        }
    },500);

    $("#input-id").on('input',fn);
})

3. Summary

Using jquery to realize that the input box loses focus after input can effectively improve the user experience. During the implementation process, we need to perform event binding, obtain the value of the input box, verify the value of the input box, and use the debounce function. At the same time, in actual development, form submission issues also need to be considered, such as how to prevent repeated submission of forms, etc.

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