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March 1, 2017 11:12
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Answers of Es6katas [http://es6katas.org/]
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// 10: destructuring - array | |
// To do: make all tests pass, leave the assert lines unchanged! | |
describe('destructuring arrays makes shorter code', () => { | |
it('extract value from array, e.g. extract 0 into x like so `let [x] = [0];`', () => { | |
let [firstValue] = [1]; | |
assert.strictEqual(firstValue, 1); | |
}); | |
it('swap two variables, in one operation', () => { | |
let [x, y] = ['ax', 'why']; | |
[x, y] = [y, x]; | |
assert.deepEqual([x, y], ['why', 'ax']); | |
}); | |
it('leading commas', () => { | |
const all = ['ax', 'why', 'zet']; | |
const [,,z] = all; | |
assert.equal(z, 'zet'); | |
}); | |
it('extract from nested arrays', () => { | |
const user = [['Some', 'One'], 23]; | |
const [[firstName, surname], age] = user; | |
const expected = 'Some One = 23 years'; | |
assert.equal(`${firstName} ${surname} = ${age} years`, expected); | |
}); | |
it('chained assignments', () => { | |
let c, d; | |
let [a, b] = [c, d] = [1, 2]; | |
assert.deepEqual([a, b, c, d], [1, 2, 1, 2]); | |
}); | |
it('in for-of loop', () => { | |
for (var [,a, b] of [[0, 1, 2]]) {} | |
assert.deepEqual([a, b], [1, 2]); | |
}); | |
}); |
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Find something bizzare : if I use these code the browser give me a hint i was right about format
it('leading commas', () => {
const all = ['ax', 'why', 'zet'];
const [,...z] = all;
assert.equal(z, ['why','zet']);
});
here is error list:
AssertionError: ["why","zet"] == ["why","zet"]
at n.eval (eval at runSpecs (spec-runner.js:95163:7), :29:12)
at r (http://cdnjs.cloudflare.com/ajax/libs/mocha/3.1.2/mocha.min.js:2:8479)
at r.run (http://cdnjs.cloudflare.com/ajax/libs/mocha/3.1.2/mocha.min.js:2:9550)
at i.runTest (http://cdnjs.cloudflare.com/ajax/libs/mocha/3.1.2/mocha.min.js:2:14329)
at http://cdnjs.cloudflare.com/ajax/libs/mocha/3.1.2/mocha.min.js:2:14969
at r (http://cdnjs.cloudflare.com/ajax/libs/mocha/3.1.2/mocha.min.js:2:13794)
at http://cdnjs.cloudflare.com/ajax/libs/mocha/3.1.2/mocha.min.js:2:13770
at n (http://cdnjs.cloudflare.com/ajax/libs/mocha/3.1.2/mocha.min.js:2:13561)
at http://cdnjs.cloudflare.com/ajax/libs/mocha/3.1.2/mocha.min.js:2:13625
at i (http://cdnjs.cloudflare.com/ajax/libs/mocha/3.1.2/mocha.min.js:1:572)