Javascript setters/getters
-
19-09-2019 - |
Question
var author = {
firstname: 'Martin',
lastname: 'Hansen'
}
function settersGetters(propStr) {
for (var i = 0; i < propStr.length; i++) {
author['_'+ propStr[i]] = null;
author.__defineGetter__(propStr[i],
function() {
return author['_'+ propStr[i]];
});
author.__defineSetter__(propStr[i],
function(val) {
author['_'+ propStr[i]] = val;
});
};
}
The above code would hopefully generate setters/getters for any supplied properties (in an array) for the object author.
But when I call the below code Both firstname and lastname is olsen.. What am I doing wrong?
settersGetters(['firstname', 'lastname']);
author.firstname = 'per';
author.lastname = 'olsen';
console.log(author.firstname);
console.log(author.lastname);
Solution
The definition is made in a closure, so all the setters are using the last value of i.
Use this instead:
function setterGetter(property)
{
author['_'+ property] = null;
author.__defineGetter__(property,
function() {
return author['_'+ property];
});
author.__defineSetter__(property,
function(val) {
author['_'+ property] = val;
});
}
function settersGetters(propStr) {
for (var i = 0; i < propStr.length; i++) {
setterGetter(propStr[i]);
};
}
OTHER TIPS
I suspect this is a closure issue, which several helpful people explained to me here.
Try wrapping the i
reference inside a function, and read up on closures. Despite all the help, I confess that I still don't really understand them.
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