I have an object array to which I'm add a new property (theNewFieldToAdd) using map, however I only want to add the property if the index is of a certain number.
Any ideas?
rows.map((row, index) => ({
...row,
theNewFieldToAdd: true
})),
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5 Answers
rows.map((row, index) => ({
...row,
...(index===MYINDEX ? {theNewFieldToAdd: true} : {})
}))
Even more concise...
rows.map((row, index) => ({
...row,
...index===MYINDEX && {theNewFieldToAdd: true}
}))
Comments
Would a ternary work?
let x = [
{a: 1, b: 2},
{a: 3, b: 4},
{a: 5, b: 6},
{a: 7, b: 8}
];
console.log(
x.map( (row, i) => (i > 2 ? {...row, newValue: true} : row) ) );.as-console-wrapper { top: 0; max-height: 100% !important; }
Comments
you don't have to make it short. logics like this can pay off to be readable.
rows.map((row, index) => {
if(index === x){
row.theNewField = true
}
return row;
})
Comments
You can use for example the short-circuit evaluation to make it a bit more concise:
let rows = [{ key: "a" }, { key: "b" }, { key: "c" }];
let result = rows.map((row, index) => ({
...row,
...(index === 0 && { theNewFieldToAdd: true }),
}));
console.log(result);
Comments
Try below working demo-
rows = [{'first': 1},{'second': 2},{'third': 3},{'fourth': 4},{'fifth': 5}];
rows1 = rows.map((row, index) => (index == 1 ? {
...row, theNewFieldToAdd: true
} : row));
console.log(rows1);