import getLength from './_getLength.js';
import isArrayLike from './_isArrayLike.js';
import isArray from './isArray.js';
import isArguments from './isArguments.js';import getLength from './_getLength.js';
import isArrayLike from './_isArrayLike.js';
import isArray from './isArray.js';
import isArguments from './isArguments.js';Internal implementation of a recursive flatten function.
export default function flatten(input, depth, strict, output) {
output = output || [];
if (!depth && depth !== 0) {
depth = Infinity;
} else if (depth <= 0) {
return output.concat(input);
}
var idx = output.length;
for (var i = 0, length = getLength(input); i < length; i++) {
var value = input[i];
if (isArrayLike(value) && (isArray(value) || isArguments(value))) {Flatten current level of array or arguments object.
if (depth > 1) {
flatten(value, depth - 1, strict, output);
idx = output.length;
} else {
var j = 0, len = value.length;
while (j < len) output[idx++] = value[j++];
}
} else if (!strict) {
output[idx++] = value;
}
}
return output;
}