Set iteration in TypeScript function not evaluating properly

Question

I keep getting this message in the console when I try and run the below code: "undefined is not an object (evaluating 'this.courseAvailThisTerm')". The courseAvailThisTerm() function works properly because it works in other contexts. Any one have an idea why I keep getting this error message? I've tried changing the for loop version but that doesn't work either.

for(let quarter of degreePlan) {
    foundationCourseSet.forEach(function(fc) {
            if(this.courseAvailThisTerm(fc, quarter.term))
                console.log("It was avail!");
        });
}

Possible duplicate of [How to access the correct \`this\` inside a callback?](https://stackoverflow.com/questions/20279484/how-to-access-the-correct-this-inside-a-callback) — CRice, May 15 '18 at 18:41

score 1 · Accepted Answer · answered May 15 '18 at 18:42

Try this:

for(let quarter of degreePlan) {
    foundationCourseSet.forEach((fc) => {
            if(this.courseAvailThisTerm(fc, quarter.term))
                console.log("It was avail!");
        });
}

I change function (fc) {..} to arrow function (fc) => {...} which preserve this in context on function execution.

Set iteration in TypeScript function not evaluating properly

1 Answers1