For example, I have codes (coffeescript) like this:
sortedLatLng = _(w)
.sortBy (x) -> x.time
.map (x) -> [x.longitude,x.latitude]
.uniq((x)-> x[0].toFixed(3) + "," + x[1].toFixed(3)) # keep three decimal to merge nearby points
console.log(sortedLatLng.value())
myFunction1(sortedLatLng.value())
myFunction2(sortedLatLng.value())
console.log(sortedLatLng.reverse().value())
This may be chained by other lodash method later. Meanwhile, its value may be necessary to be extracted. I was justing wonder whether it will cache the result. I didn't find how it is implemented in its documentation..
Will it be calculated once or twice for:
myFunction1(sortedLatLng.value())
myFunction2(sortedLatLng.value())
Does anyone have ideas about this?
When you create a lodash wrapper, the wrapped value is stored within the wrapper. For example:
var wrapper = _([ 1, 2, 3 ]);
Here, [ 1, 2, 3 ]
is stored in wrapper
, and any chained operations added to the wrapper are passed this value. Chained operations are stored , not executed. For example:
var wrapper = _([ 1, 2, 3 ]).map(function(item) {
console.log('mapping');
return item;
});
This code creates a wrapper with a map()
operation, but doesn't execute it. Instead, it stores the chained operations so that when value()
is called, it can execute them:
var wrapper = _([ 1, 2, 3 ]).map(function(item) {
console.log('mapping');
return item;
});
wrapper.value()
// mapping
// ...
Calling value()
again on this wrapper will simply repeat the same operations on the wrapped value - results aren't cached.
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