File Reader from File object in Salesforce

ViewFile.cmp

<aura:component
  controller="FileReader"
  implements="force:appHostable,flexipage:availableForAllPageTypes,flexipage:availableForRecordHome,force:hasRecordId,forceCommunity:availableForAllPageTypes,force:lightningQuickAction"
  access="global">
  <aura:attribute name="data" type="String" />
  <aura:attribute name="previewUrl" type="String" />
  <aura:attribute name="urlLink" type="String" />
  <aura:attribute name="recordId" type="String" />
  <aura:attribute name="files" type="object[]" />
  <aura:attribute name="file" type="object" />
  <aura:attribute name="showFileLink" type="boolean" />
  <lightning:button variant="brand" label="View Files" onclick="{!c.getSpecificFile}" /><br/>
     <aura:if isTrue="{!v.showFileLink}">
       	 <a href="{!'data:' + v.file.ContentType+';base64,'+v.file.Content}">Download File</a><br/>
         <a href="{!v.file.FileUrl}">Preview File</a><br/>
         <a href="{!v.file.DownloadUrl}">Download using Link</a>
  	</aura:if>
  
    <lightning:button variant="brand" label="View Case Files" onclick="{!c.getCaseFiles}" /><br/>
     <aura:iteration items="{!v.files}" var="f">
       	 <a href="{!'data:' + f.ContentType+';base64,'+f.Content}">Download File</a><br/>
         <a href="{!f.FileUrl}">Preview File</a><br/>
         <a href="{!f.DownloadUrl}">Download using Link</a><br/>
    </aura:iteration>
    
</aura:component>

ViewFileController.js

({
	getSpecificFile : function(component, event, helper) {
        var recordId=component.get("v.contentdocumentId");
        //Remove hardcoding based on your record
       	helper.requestFiledata(component, event,'0692v00000D1pBIAAZ','');
	},
    getCaseFiles : function(component, event, helper) {
    	var recordId=component.get("v.recordId");
       //Remove hardcoding based on your record
    	helper.requestFiledata(component, event, '5002v00002g58RPAAY','entity');
	}
})

ViewFileHelper.js

({
    requestFiledata: function(component, event,recordid,type) {
        //**dataURL to blob**
        function dataURLtoBlob(dataurl) {
            var arr = dataurl.split(","),
                mime = arr[0].match(/:(.*?);/)[1],
                bstr = atob(arr[1]),
                n = bstr.length,
                u8arr = new Uint8Array(n);
            while (n--) {
                u8arr[n] = bstr.charCodeAt(n);
            }
            return new Blob([u8arr], { type: mime });
        }
        
        //**blob to dataURL**
        function blobToDataURL(blob, callback) {
            var a = new FileReader();
            a.onload = function(e) {
                callback(e.target.result);
            };
            a.readAsDataURL(blob);
        }
        var action = type=='entity'?component.get("c.GetEntityRecordFiles"):component.get("c.GetFile");
        action.setParams({
            recordId: recordid
        });
        action.setCallback(this, function(a) {
            var state = a.getState();
            if (state == "SUCCESS") {
                var res = a.getReturnValue();
                component.set(type=='entity'?"v.files":"v.file", res);
            }
        });
        $A.enqueueAction(action);
    }
});