对象属性返回文字的一部分

Question

I am new to JavaScript Objects and i got a list of object and in that object there is a property called signature which is BLOB, I am trying to decode it so I can display it as image, but when I use it, I am unable to use it.upon debugging in console, the returned item is a number but it has following structure

"{
  "signature": "/9j/4AA"

but when I do console.log(typeof + deca); it says number, following is my code

    for (const sign of result){
        const deca = atob(sign.signature);
        console.log(typeof + deca);

console.log(deca) I get this

and using it to display like

            <img *ngFor="let sign of selectedUser"
                 [src]="sign.imageData"
                 alt="">

Do I need to use trim or slice to cut off the "{ "signature": part or I am doing something wrong?

Answer 1

this happens because of the + operator, which automatically makes the variable a number .

https://jsfiddle.net/n97ssLma/

 var test = "test" alert(typeof test) //string alert(typeof + test) //number 

to display your blob as an image do the following:

 var image = document.createElement('img'); image.src="data:image/gif;base64,R0lGODlhDwAPAKECAAAAzMzM/////wAAACwAAAAADwAPAAACIISPeQHsrZ5ModrLlN48CXF8m2iQ3YmmKqVlRtW4MLwWACH+H09wdGltaXplZCBieSBVbGVhZCBTbWFydFNhdmVyIQAAOw=="; image.width=100; image.height=100; image.alt="here should be some image"; document.body.appendChild(image); 

Using Javascript to Display Blob

updated your fiddle: https://jsfiddle.net/jt5ks76z/1/

example using atob method:

https://jsfiddle.net/jt5ks76z/4/