检查文件大小限制

Question

i need help in checking file size before uploading file,

i want to check the size of file and then continue to upload

  $("form#data").submit(function(e) {
        e.preventDefault();   
        if(this.files[0].size > 2097152){
           alert("File is too big!");
           this.value = "";
           return false;
        };  
        var formData = new FormData(this);
    
        $.ajax({
            url: window.location.pathname,
            type: 'POST',
            data: formData,
            success: function (data) {
                alert(data)
            },
            cache: false,
            contentType: false,
            processData: false
        });
    });
    
    
    <form id="data" method="post" enctype="multipart/form-data">
        <input name="image" type="file" />
        <button>Submit</button>
    </form>

Answer 1

You need to get the files from the file input object whereas your current code is trying to get them from this which refers to the entire form.

 $("form#data").submit(function(e) { e.preventDefault(); const file_input = $(this).find('input[name="image"]')[0]; console.log(file_input.files[0].size); if (file_input.files[0].size > 2097152) { alert("File is too big!"); this.value = ""; return false; }; console.log("safe to upload..."); });

 <script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script> <form id="data" method="post" enctype="multipart/form-data"> <input name="image" type="file" /> <button>Submit</button> </form>