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chaining_spec.js
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67 lines (63 loc) · 2.08 KB
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function deepEqual(actual, expected, description) {
it(description, function() {
expect(actual).toEqual(expected);
});
}
function ok(actual, description) {
expect(actual).toBe(true);
}
describe('map/flatten/reduce', function() {
var lyrics = [
"I'm a lumberjack and I'm okay",
"I sleep all night and I work all day",
"He's a lumberjack and he's okay",
"He sleeps all night and he works all day"
];
var counts = _(lyrics).chain()
.map(function(line) { return line.split(''); })
.flatten()
.reduce(function(hash, l) {
hash[l] = hash[l] || 0;
hash[l]++;
return hash;
}, {}).value();
ok(counts.a == 16 && counts.e == 10, 'counted all the letters in the song');
});
describe('select/reject/sortBy', function() {
var numbers = [1,2,3,4,5,6,7,8,9,10];
numbers = _(numbers).chain().select(function(n) {
return n % 2 === 0;
}).reject(function(n) {
return n % 4 === 0;
}).sortBy(function(n) {
return -n;
}).value();
deepEqual(numbers, [10, 6, 2], 'filtered and reversed the numbers');
});
describe('select/reject/sortBy in functional style', function() {
var numbers = [1,2,3,4,5,6,7,8,9,10];
numbers = _.chain(numbers).select(function(n) {
return n % 2 === 0;
}).reject(function(n) {
return n % 4 === 0;
}).sortBy(function(n) {
return -n;
}).value();
deepEqual(numbers, [10, 6, 2], 'filtered and reversed the numbers');
});
describe('reverse/concat/unshift/pop/map', function() {
var numbers = [1,2,3,4,5];
numbers = _(numbers).chain()
.reverse()
.concat([5, 5, 5])
.unshift(17)
.pop()
.map(function(n){ return n * 2; })
.value();
deepEqual(numbers, [34, 10, 8, 6, 4, 2, 10, 10], 'can chain together array functions.');
});
describe('chaining works in small stages', function() {
var o = _([1, 2, 3, 4]).chain();
deepEqual(o.filter(function(i) { return i < 3; }).value(), [1, 2]);
deepEqual(o.filter(function(i) { return i > 2; }).value(), [3, 4]);
});