When using jQuery Ajax to submit files asynchronously, an uncaught type error: illegal invocation error is reported. The error information is shown in the figure below:

error reason:

When using Ajax to send data to the background, the parameter type of the image data is file, which belongs to the object, not a string value. Causes the error to appear

var formData = new FormData();

formData.append(“src”, 2);

formData.append(“file”,imgFile);

First of all, we will see if the above problems are caused by the wrong writing of parameters. If it is written as an object by mistake, please modify the corresponding parameter type. If you are sure that one of the data to be uploaded is object type, please add it in the Ajax parameter

processData: false

contentType : false

　　　　  $.ajax({
              url: 'Transmission address',
              type: 'POST',
              cache: false,    //Uploading files without caching
              data: formData,
              processData: false, // Tells jQuery not to process the data sent
              contentType: false, // tells jQuery not to set the Content-Type request header
              success: function (res) {
                    console.log(res)
                    if(res.ret == 0){
                        console.log(Upload successful)
                    }
                },
                error: function (err) {
                    console.log(err)
                }
            })

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