Avoid using an element's index as the
key prop JS-0437Do not use Array index in keys
158 }
159 const pwChecks = passwordRequirements.map((requirement, index) => (
160 <PasswordRequirement
161 key={index}162 label={requirement.label}
163 meets={requirement.re.test(form.values.password)}
164 />Do not use Array index in keys
151 inputContainer={(children) => <Stack spacing={4}>{children}</Stack>}
152 >
153 <Checkbox
154 key={`${item.id}-${par}-item`}155 label={`${item.icon} ${t(item.tsKey, { ns: item.tsNs })}`}
156 {...form.getInputProps(`formOptions.communities.${par}.id`)}
157 />Do not use Array index in keys
145 }
146
147 return (
148 <div key={`${item.id}-${par}`}>149 <Checkbox.Group
150 {...form.getInputProps('communityFocus')}
151 inputContainer={(children) => <Stack spacing={4}>{children}</Stack>}Do not use Array index in keys
133 >
134 {item.children.map((child, i) => (
135 <Checkbox
136 key={`${child.id}-${par}-${i}`}137 label={t(child.tsKey, { ns: child.tsNs })}
138 pl={40}
139 {...form.getInputProps(`formOptions.communities.${par}.children.${i}.id`)}Do not use Array index in keys
133 >
134 {item.children.map((child, i) => (
135 <Checkbox
136 key={`${child.id}-${par}-${i}`}137 label={t(child.tsKey, { ns: child.tsNs })}
138 pl={40}
139 {...form.getInputProps(`formOptions.communities.${par}.children.${i}.id`)}
Description
When rendering a list of items in React, it is necessary to pass a "key" prop.
This key is used by React to identify which items have changed, are added, or are removed and should be stable.
It is not recommended to use the index of an element as key because it doesn't uniquely identify the element.
When elements are added/removed from an array, the index of an element may change, which will result in unnecessary re-renders.
When the array is sorted, or an element is added to the beginning of the array, the indices will be changed even though the element representing an index may stay the same. This too can result in unnecessary renders.
Bad Practice
cards.map((cardData, index) => (
<Card key={`key-is-${index}`} data={cardData}/>
));
buttonNames.map((btnText, index) => (
<Button key={index} text={btnText}/>
));
things.forEach((thing, index) => {
otherThings.push(<Hello key={index} />);
});
Recommended
cards.map((cardData) => (
<Card key={cardData.id} data={cardData} />
));
buttonData.forEach((btnData) => {
buttons.push(<Hello key={btnData.id} text={btnData.text} />);
});