Upload the image only after validating the image size in express js

Here is my code to check the image size and width that matches the criteria

im.identify(req.files.image,function (err,features) {      
   //console.log(features);                                
    if(features.width<1000){                               
        console.log('need bigger size');                   
    }                                                      
  });  
 //upload code here
 beginUpload();

Since its asynchronous the beginUpload() function is invoked early so how can i check the image size synchronously. ie i want to upload the image that pass the size criteria

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