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Copy path5 - Asymmetrical reading and writing.js
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54 lines (46 loc) · 1.98 KB
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Copy path5 - Asymmetrical reading and writing.js
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54 lines (46 loc) · 1.98 KB
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var authorClone = clone(Author);
alert(authorClone.name); // Linked to the primative Person.name, which is the
// string 'default name'.
authorClone.name = 'new name'; // A new primative is created and added to the
// authorClone object itself.
alert(authorClone.name); // Now linked to the primative authorClone.name, which
// is the string 'new name'.
authorClone.books.push('new book'); // authorClone.books is linked to the array
// Author.books. We just modified the
// prototype object's default value, and all
// other objects that link to it will now
// have a new default value there.
authorClone.books = []; // A new array is created and added to the authorClone
// object itself.
authorClone.books.push('new book'); // We are now modifying that new array.
var CompoundObject = {
string1: 'default value',
childObject: {
bool: true,
num: 10
}
}
var compoundObjectClone = clone(CompoundObject);
// Bad! Changes the value of CompoundObject.childObject.num.
compoundObjectClone.childObject.num = 5;
// Better. Creates a new object, but compoundObject must know the structure
// of that object, and the defaults. This makes CompoundObject and
// compoundObjectClone tightly coupled.
compoundObjectClone.childObject = {
bool: true,
num: 5
};
// Best approach. Uses a method to create a new object, with the same structure and
// defaults as the original.
var CompoundObject = {};
CompoundObject.string1 = 'default value',
CompoundObject.createChildObject = function() {
return {
bool: true,
num: 10
}
};
CompoundObject.childObject = CompoundObject.createChildObject();
var compoundObjectClone = clone(CompoundObject);
compoundObjectClone.childObject = CompoundObject.createChildObject();
compoundObjectClone.childObject.num = 5;