check for the empty string to detect a non answer === was causing other tests to fail when they should not have due to type mismatches. Since all values from the text input box are strings === caused them to fail against their proper types from the trace information.

bnmnetp · bnmnetp · commit 8d6745596fce · 2013-07-31T08:35:10.000-05:00
diff --git a/v3/js/pytutor.js b/v3/js/pytutor.js
@@ -3449,7 +3449,7 @@ function traceQCheckMe(inputId, divId, answer) {
        correctAns = correctAns[attrs[j]]
    }
    feedbackElement = $("#" + divId + "_feedbacktext")
-   if (ans === correctAns) { // do an exact match so that "" doesn't spuriously get matched with 0
+   if (ans.length > 0 && ans == correctAns) {
        feedbackElement.html('Correct')
    } else {
        feedbackElement.html(vis.curTrace[i].question.feedback)

Original file line number	Diff line number	Diff line change
`@@ -3449,7 +3449,7 @@ function traceQCheckMe(inputId, divId, answer) {`
`3449`	`3449`	`correctAns = correctAns[attrs[j]]`
`3450`	`3450`	`}`
`3451`	`3451`	`feedbackElement = $("#" + divId + "_feedbacktext")`
`3452`		`- if (ans === correctAns) { // do an exact match so that "" doesn't spuriously get matched with 0`
	`3452`	`+ if (ans.length > 0 && ans == correctAns) {`
`3453`	`3453`	`feedbackElement.html('Correct')`
`3454`	`3454`	`} else {`
`3455`	`3455`	`feedbackElement.html(vis.curTrace[i].question.feedback)`