Nonequality for Javascript String and Variable

Question

I'm trying to check whether an array, called ruleFolderNames, contains a string, using the .includes() Javascript method. The string I am checking is "Centers For Medicare & Medicaid Services".

ruleFolderNames.includes("Centers For Medicare & Medicaid Services"); // true

However, I'm not typing the string directly, I'm using a variable (called department). I've found that the department variable is not equal to the first item in the array, Centers For Medicare & Medicaid Services, even though they appear to be the same.

Here are the console.log statements:

    ruleFolderNames[0]; // Centers For Medicare & Medicaid Services
    typeof ruleFolderNames[0]; // string

    department; // Centers For Medicare & Medicaid Services
    typeof department; // string

But in fact, the variable department is not equal to the string I'm searching for.

department == "Centers For Medicare & Medicaid Services" // OUTPUTS FALSE!!!

I've included the link to my full Github repository if that's useful, the bug is contained on line 36 of this file.

There's not enough information in the question itself to answer, but I would start at checking the .length of each string, and if that doesn't pan out, compare the charCodes of each string. for (const letter of department) console.log(letter.charCodeAt(0)); Find the first that doesn't match (or use a for loop and do something when department[i] !== ruleFolderNames[0][i]) — CertainPerformance
– CertainPerformance, Commented Oct 31, 2018 at 2:11

jfriend00 · Accepted Answer · 2018-10-31 04:28:37Z

Since we don't have the actual data ourselves to debug, we can't tell you exactly what difference there is. Here are a number of things to look for:

Check the length of both strings to see if there might be a difference in leading or trailing whitespace that isn't obvious in the console. You can also output in the console with quotes surrounding it to see exactly what might be on the start or end such as console.log(`'${department}'`) and ruleFolderNames.forEach(item => console.log(`'${item}'`)).
White space characters might be different, but look like regular whitespace in the console. If you suspect the difference is in the department variable (which it appears it is), then you can normalize the whitespace with department.replace(/\s/g, " ") which converts all regex whitespace characters to a single space.
There could be some character that looks similar, but is actually a different char code.

Since you say that department == "Centers For Medicare & Medicaid Services" is false, I'd suggest the following debug code (with your department variable passed to testStr():

function testStr(testVal, targetStr) {
        console.log("-------------");
        if (testVal === targetStr) {
            console.log("two strings are the same");
            return;
        } 
        if (testVal.length !== targetStr.length) {
            console.log("two strings are different length");
            if (testVal.trim() === targetStr) {
                console.log("Found it: testVal.trim() === targetStr");
                return;
            } else {
                console.log("testVal.trim() !== targetStr, trimming whitespace off ends is not enough");
            }
            testVal = testVal.trim();
        }
        if (testVal.replace(/\s/g, " ") === targetStr) {
            console.log("replacing whitespace makes a match")
            return;
        }
        // still no match, so lets output each separate character as a char code
        // to manually see what's different
        console.log("testVal = ", testVal.split("").map(item => item.charCodeAt(0)).join(","));
        console.log("targetStr = ", targetStr.split("").map(item => item.charCodeAt(0)).join(","));
    }
    
    const testValues = [
        " Centers For Medicare & Medicaid Services",  // leading whitespace
        "Centers For Medicare & Medicaid Services ",  // trailing whitespace
        "Centers\tFor Medicare & Medicaid Services",  // tab for whitespace
        "C℮nters For Medicare & Medicaid Services",   // odd first e in Centers
        "Cënters For Medicare & Medicaid Services"    // odd first e in Centers
    ];

    for (let t of testValues) {
       testStr(t, "Centers For Medicare & Medicaid Services");
    }

Thank you. There was a trailing white space in the variable that I couldn't see.

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