1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
|
var isIterateeCall = require('../internal/isIterateeCall');
/* Native method references for those with the same name as other `lodash` methods. */
var nativeCeil = Math.ceil,
nativeMax = Math.max;
/**
* Creates an array of numbers (positive and/or negative) progressing from
* `start` up to, but not including, `end`. If `end` is not specified it's
* set to `start` with `start` then set to `0`. If `end` is less than `start`
* a zero-length range is created unless a negative `step` is specified.
*
* @static
* @memberOf _
* @category Utility
* @param {number} [start=0] The start of the range.
* @param {number} end The end of the range.
* @param {number} [step=1] The value to increment or decrement by.
* @returns {Array} Returns the new array of numbers.
* @example
*
* _.range(4);
* // => [0, 1, 2, 3]
*
* _.range(1, 5);
* // => [1, 2, 3, 4]
*
* _.range(0, 20, 5);
* // => [0, 5, 10, 15]
*
* _.range(0, -4, -1);
* // => [0, -1, -2, -3]
*
* _.range(1, 4, 0);
* // => [1, 1, 1]
*
* _.range(0);
* // => []
*/
function range(start, end, step) {
if (step && isIterateeCall(start, end, step)) {
end = step = undefined;
}
start = +start || 0;
step = step == null ? 1 : (+step || 0);
if (end == null) {
end = start;
start = 0;
} else {
end = +end || 0;
}
// Use `Array(length)` so engines like Chakra and V8 avoid slower modes.
// See https://youtu.be/XAqIpGU8ZZk#t=17m25s for more details.
var index = -1,
length = nativeMax(nativeCeil((end - start) / (step || 1)), 0),
result = Array(length);
while (++index < length) {
result[index] = start;
start += step;
}
return result;
}
module.exports = range;
|
