javascript - Cannot read properties of undefined (reading 'tagName') - Stack Overflow

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I don't know why it's returning error with tagName. is subLabel wrong?

for (var ind = 0; ind < target.length; ind++)
    {
        var target = target[ind]
        for (var ind; ind < target.childNodes.length; ind++);
        {
            const subLabel = target.childNodes[ind];
            if (subLabel.tagName == "SPAN" || subLabel.tagName == "LI") //error line
            {
                //do something with label
            }
            typeDisplay(subLabel);
        }  
    }

I don't know why it's returning error with tagName. is subLabel wrong?

for (var ind = 0; ind < target.length; ind++)
    {
        var target = target[ind]
        for (var ind; ind < target.childNodes.length; ind++);
        {
            const subLabel = target.childNodes[ind];
            if (subLabel.tagName == "SPAN" || subLabel.tagName == "LI") //error line
            {
                //do something with label
            }
            typeDisplay(subLabel);
        }  
    }

• javascript
• html

Share Improve this question Follow asked Jan 15, 2022 at 13:04 eattatoeattato 1311 gold badge11 silver badge55 bronze badges

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3 Answers 3

Sorted by: Reset to default 1

You are using var ind twice. Use let instead. Read this

You are using the same variable name in both inner and outer for loop (ie. var ind).

what you can do here is either change the variable name in the inner loop or change the variable name in the outer loop.

It's mon for nested loops, to use a different loop variable, such as while the outer loop uses var i=0; the inner loop uses var j=0;.

The posted code, the 2nd var ind is duplicated, because it shares the same variable scope of the 1st var.

I don't know why it's returning error with tagName. is subLabel wrong?

for (var ind = 0; ind < target.length; ind++)
    {
        var target = target[ind]
        for (var ind; ind < target.childNodes.length; ind++);
        {
            const subLabel = target.childNodes[ind];
            if (subLabel.tagName == "SPAN" || subLabel.tagName == "LI") //error line
            {
                //do something with label
            }
            typeDisplay(subLabel);
        }  
    }

I don't know why it's returning error with tagName. is subLabel wrong?

for (var ind = 0; ind < target.length; ind++)
    {
        var target = target[ind]
        for (var ind; ind < target.childNodes.length; ind++);
        {
            const subLabel = target.childNodes[ind];
            if (subLabel.tagName == "SPAN" || subLabel.tagName == "LI") //error line
            {
                //do something with label
            }
            typeDisplay(subLabel);
        }  
    }

• javascript
• html

Share Improve this question Follow asked Jan 15, 2022 at 13:04 eattatoeattato 1311 gold badge11 silver badge55 bronze badges

Add a ment  | 

3 Answers 3

Sorted by: Reset to default 1

You are using var ind twice. Use let instead. Read this

You are using the same variable name in both inner and outer for loop (ie. var ind).

what you can do here is either change the variable name in the inner loop or change the variable name in the outer loop.

It's mon for nested loops, to use a different loop variable, such as while the outer loop uses var i=0; the inner loop uses var j=0;.

The posted code, the 2nd var ind is duplicated, because it shares the same variable scope of the 1st var.

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