West Midlands | ITP-Sept-25 | Georgina Rogers | Sprint 2 | Coursework Sprint 2 #862
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zilinskyte
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Sprint-2/implement/tally.js
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| if (!Array.isArray(items)) { | ||
| throw new Error("Input must be an array"); | ||
| } | ||
| const counts = {}; // empty object to store tally of key-value pairs |
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Does the following function call returns the value you expect?
tally(["toString", "toString"]);
Suggestion: Look up an approach to create an empty object with no inherited properties.
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this is my output: [Object: null prototype] { toString: 2 }
is this correct?
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Yes. This is because the object no longer has an inherited toString() method.
The purpose of using Object.create(null) is so that, when the created object is used as a lookup table, it can accept any string as its property.
An alternative approach is to use a Map object as a lookup table.
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| // a) What is the current return value when invert is called with { a : 1 } | ||
| // { '1': 'a' } | ||
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| // b) What is the current return value when invert is called with { a: 1, b: 2 } | ||
| // { '1': 'a', '2': 'b' } |
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The "current return value" in questions (a), (b), and (d) refers to the value returned by the original (unmodified) function.
The objects you described on line 28 and 31 are not the objects returned by the original function.
The explanation given on line 41 (answer to question (d)) is also not quite correct.
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I have rewritten my answer for (d) , I am struggling to understand if you mean my answers to (a) and (b) are incorrect, or if it was just the explanation that was incorrect?
cjyuan
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zilinskyte
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Learners, PR Template
Self checklist
Changelist
Bugs predicted, tested and fixed.
Implement functions based off a set of requirements.
Interpret a program.
Questions
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