CODEWITHSUNDEEP
javascripthtmlgoogle-chrome
RAN
RAN

Reputation: 101

Reading a file in chrome

I am trying to write a java script to read a file in chrome and I am using the javascript debugger of chrome. here is the script:

function myFunction()
{
alert("I am an alert box!");
var e ;
var contents;
var control = document.getElementById("myfile");
  files = control.files;
console.log("Filename: " + files[0].name);
var reader = new FileReader();
reader.readAsText(files[0]);

reader.onload = function (e) { 


    contents = e.target.result;

    };

console.log("File contents: " + contents);
console.log("I am an alert box!");console.log("I am an alert box!");



}





</script>

when i run the code the contents variable is undefined. Plenty of discussion has gone into this but i have not found a solution. I am using the --allow-file-acess-from-files option. Now the following code works in a strange manner:

<script>
function myFunction()
{
alert("I am an alert box!");
var e ;
var contents;
var control = document.getElementById("myfile");
  files = control.files;
console.log("Filename: " + files[0].name);
var reader = new FileReader();
reader.readAsText(files[0]);

reader.onload = function (e) {
    contents = e.target.result ;
    };
console.log(e.target.result);
console.log("I am an alert box!");console.log("I am an alert box!");
}
</script>

It throws an error which is "Uncaught TypeError: Cannot read property 'target' of undefined" However in the watch expression window the following variables show that the file is being read.

event.target.result: "firmware file ↵:10000000782600204D4B0000B94B0000B94B000092 ↵:10001000B94B0000B94B0000B94B000000000000D4 ↵:10002000000000000000000000000000B94B0000CC ↵:10003000B94B000000000000B94B0000210B00008C ↵:10004000B94B0000B94B0000B94B0000B94B0000A0 ↵:10005000B94B0000B94B0000B94B0000B94B000090 ↵:10006000B94B0000B94B0000B94B0000B94B000080 ↵:10007000B94B0000B94B0000B94B0000B94B000070 ↵:10008000B94B0000B94B0000B94B0000B94B000060 and the same ouput for e.target.result and contents variable.

Why is the code behaviour is so wierd? Kindly help me out. I am not very skilled with javascripting.

Upvotes: 0

Views: 443

Answers (1)

Collin Grady
Collin Grady

Reputation: 2242

e.target will be undefined on your 2nd console.log there towards the bottom - only one is inside your onload function, and therefore has e set.

The second one is acting on the var e ; you defined at the top, which is null, and therefore e.target.result is invalid.

e: in other words, delete this line, or move it into the function:

bogus line

Upvotes: 1

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