How can one pass a variable to a filter function in javascript?
In this case I'm trying to pass a value to variable "maxage":
var dateFilter = function(value,maxage) { // Age in miliseconds
if(Date.now() - value < maxage) {
return value;
} else {
return false;
}
}
dates.filter(dateFilter,500);
How can I pass the value 500 to the filter as maxage?
You would need to invoke Function.prototype.bind to create something similar to a default argument.
dates.filter(dateFilter.bind( null, 500 ));
dateFilter callback would then called with 500 PLUS "automatic passed in values" value, index, array.
function dateFilter( customArgument, value, index, array ) {
// customArgument === 500
}
function dateFilter( customArgument, value, index, array ) {
maxage has been bound to this. Consider the following:
var dateFilter = function(value) {
if(value < this) return value;
}
var dates = [1,2,3];
console.log(dates.filter(dateFilter,2));
> [1] // Output.
The MDN documentation shows the filter signature to be array.filter(callback[, thisObject])
Maybe there is no need to overcomplicate the things, try the simple way:
var maxage = 500,
newDates = dates.filter(function(value) {
return Date.now() - value < maxage;
});
