Array-index access to specific mapped data.
If the map function hasn't ran yet on the source data, it will be ran, an cached for subsequent accesses.
class Foo {
myMappedData = map(this, {
data: () => [1, 2, 3],
map: (num) => `hi, ${num}!`
});
get first() {
return this.myMappedData[0];
}
}
Without evaluating the map function on each element, provide the total number of elements
class Foo {
myMappedData = map(this, {
data: () => [1, 2, 3],
map: (num) => `hi, ${num}!`
});
get numItems() {
return this.myMappedData.length;
}
}
evaluate and return an array of all mapped items.
This is useful when you need to do other Array-like operations on the mapped data, such as filter, or find
class Foo {
myMappedData = map(this, {
data: () => [1, 2, 3],
map: (num) => `hi, ${num}!`
});
get everything() {
return this.myMappedData.values();
}
}
Iterate over the mapped array, lazily invoking the passed map function that was passed to [[map]].
This will always return previously mapped records without re-evaluating
the map function, so the default {{#each}} behavior in ember will
be optimized on "object-identity". e.g.:
// ...
myMappedData = map(this, {
data: () => [1, 2, 3],
map: (num) => `hi, ${num}!`
});
// ...
{{#each this.myMappedData as |datum|}}
loop body only invoked for changed entries
{{datum}}
{{/each}}
Iteration in javascript is also provided by this iterator
class Foo {
myMappedData = map(this, {
data: () => [1, 2, 3],
map: (num) => `hi, ${num}!`
});
get mapAgain() {
let results = [];
for (let datum of this.myMappedData) {
results.push(datum);
}
return datum;
}
}
Public API of the return value of the [[map]] utility.