/node-v4.1.0-windows-x86/lib/node_modules/npm/node_modules/request/node_modules/qs/Readme.md
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- # qs
- A querystring parsing and stringifying library with some added security.
- [![Build Status](https://secure.travis-ci.org/hapijs/qs.svg)](http://travis-ci.org/hapijs/qs)
- Lead Maintainer: [Nathan LaFreniere](https://github.com/nlf)
- The **qs** module was originally created and maintained by [TJ Holowaychuk](https://github.com/visionmedia/node-querystring).
- ## Usage
- ```javascript
- var Qs = require('qs');
- var obj = Qs.parse('a=c'); // { a: 'c' }
- var str = Qs.stringify(obj); // 'a=c'
- ```
- ### Parsing Objects
- ```javascript
- Qs.parse(string, [options]);
- ```
- **qs** allows you to create nested objects within your query strings, by surrounding the name of sub-keys with square brackets `[]`, or prefixing the sub-key with a dot `.`.
- For example, the string `'foo[bar]=baz'` converts to:
- ```javascript
- {
- foo: {
- bar: 'baz'
- }
- }
- ```
- When using the `plainObjects` option the parsed value is returned as a plain object, created via `Object.create(null)` and as such you should be aware that prototype methods will not exist on it and a user may set those names to whatever value they like:
- ```javascript
- Qs.parse('a.hasOwnProperty=b', { plainObjects: true });
- // { a: { hasOwnProperty: 'b' } }
- ```
- By default parameters that would overwrite properties on the object prototype are ignored, if you wish to keep the data from those fields either use `plainObjects` as mentioned above, or set `allowPrototypes` to `true` which will allow user input to overwrite those properties. *WARNING* It is generally a bad idea to enable this option as it can cause problems when attempting to use the properties that have been overwritten. Always be careful with this option.
- ```javascript
- Qs.parse('a.hasOwnProperty=b', { allowPrototypes: true });
- // { a: { hasOwnProperty: 'b' } }
- ```
- URI encoded strings work too:
- ```javascript
- Qs.parse('a%5Bb%5D=c');
- // { a: { b: 'c' } }
- ```
- You can also nest your objects, like `'foo[bar][baz]=foobarbaz'`:
- ```javascript
- {
- foo: {
- bar: {
- baz: 'foobarbaz'
- }
- }
- }
- ```
- By default, when nesting objects **qs** will only parse up to 5 children deep. This means if you attempt to parse a string like
- `'a[b][c][d][e][f][g][h][i]=j'` your resulting object will be:
- ```javascript
- {
- a: {
- b: {
- c: {
- d: {
- e: {
- f: {
- '[g][h][i]': 'j'
- }
- }
- }
- }
- }
- }
- }
- ```
- This depth can be overridden by passing a `depth` option to `Qs.parse(string, [options])`:
- ```javascript
- Qs.parse('a[b][c][d][e][f][g][h][i]=j', { depth: 1 });
- // { a: { b: { '[c][d][e][f][g][h][i]': 'j' } } }
- ```
- The depth limit helps mitigate abuse when **qs** is used to parse user input, and it is recommended to keep it a reasonably small number.
- For similar reasons, by default **qs** will only parse up to 1000 parameters. This can be overridden by passing a `parameterLimit` option:
- ```javascript
- Qs.parse('a=b&c=d', { parameterLimit: 1 });
- // { a: 'b' }
- ```
- An optional delimiter can also be passed:
- ```javascript
- Qs.parse('a=b;c=d', { delimiter: ';' });
- // { a: 'b', c: 'd' }
- ```
- Delimiters can be a regular expression too:
- ```javascript
- Qs.parse('a=b;c=d,e=f', { delimiter: /[;,]/ });
- // { a: 'b', c: 'd', e: 'f' }
- ```
- Option `allowDots` can be used to disable dot notation:
- ```javascript
- Qs.parse('a.b=c', { allowDots: false });
- // { 'a.b': 'c' } }
- ```
- ### Parsing Arrays
- **qs** can also parse arrays using a similar `[]` notation:
- ```javascript
- Qs.parse('a[]=b&a[]=c');
- // { a: ['b', 'c'] }
- ```
- You may specify an index as well:
- ```javascript
- Qs.parse('a[1]=c&a[0]=b');
- // { a: ['b', 'c'] }
- ```
- Note that the only difference between an index in an array and a key in an object is that the value between the brackets must be a number
- to create an array. When creating arrays with specific indices, **qs** will compact a sparse array to only the existing values preserving
- their order:
- ```javascript
- Qs.parse('a[1]=b&a[15]=c');
- // { a: ['b', 'c'] }
- ```
- Note that an empty string is also a value, and will be preserved:
- ```javascript
- Qs.parse('a[]=&a[]=b');
- // { a: ['', 'b'] }
- Qs.parse('a[0]=b&a[1]=&a[2]=c');
- // { a: ['b', '', 'c'] }
- ```
- **qs** will also limit specifying indices in an array to a maximum index of `20`. Any array members with an index of greater than `20` will
- instead be converted to an object with the index as the key:
- ```javascript
- Qs.parse('a[100]=b');
- // { a: { '100': 'b' } }
- ```
- This limit can be overridden by passing an `arrayLimit` option:
- ```javascript
- Qs.parse('a[1]=b', { arrayLimit: 0 });
- // { a: { '1': 'b' } }
- ```
- To disable array parsing entirely, set `parseArrays` to `false`.
- ```javascript
- Qs.parse('a[]=b', { parseArrays: false });
- // { a: { '0': 'b' } }
- ```
- If you mix notations, **qs** will merge the two items into an object:
- ```javascript
- Qs.parse('a[0]=b&a[b]=c');
- // { a: { '0': 'b', b: 'c' } }
- ```
- You can also create arrays of objects:
- ```javascript
- Qs.parse('a[][b]=c');
- // { a: [{ b: 'c' }] }
- ```
- ### Stringifying
- ```javascript
- Qs.stringify(object, [options]);
- ```
- When stringifying, **qs** always URI encodes output. Objects are stringified as you would expect:
- ```javascript
- Qs.stringify({ a: 'b' });
- // 'a=b'
- Qs.stringify({ a: { b: 'c' } });
- // 'a%5Bb%5D=c'
- ```
- Examples beyond this point will be shown as though the output is not URI encoded for clarity. Please note that the return values in these cases *will* be URI encoded during real usage.
- When arrays are stringified, by default they are given explicit indices:
- ```javascript
- Qs.stringify({ a: ['b', 'c', 'd'] });
- // 'a[0]=b&a[1]=c&a[2]=d'
- ```
- You may override this by setting the `indices` option to `false`:
- ```javascript
- Qs.stringify({ a: ['b', 'c', 'd'] }, { indices: false });
- // 'a=b&a=c&a=d'
- ```
- You may use the `arrayFormat` option to specify the format of the output array
- ```javascript
- Qs.stringify({ a: ['b', 'c'] }, { arrayFormat: 'indices' })
- // 'a[0]=b&a[1]=c'
- Qs.stringify({ a: ['b', 'c'] }, { arrayFormat: 'brackets' })
- // 'a[]=b&a[]=c'
- Qs.stringify({ a: ['b', 'c'] }, { arrayFormat: 'repeat' })
- // 'a=b&a=c'
- ```
- Empty strings and null values will omit the value, but the equals sign (=) remains in place:
- ```javascript
- Qs.stringify({ a: '' });
- // 'a='
- ```
- Properties that are set to `undefined` will be omitted entirely:
- ```javascript
- Qs.stringify({ a: null, b: undefined });
- // 'a='
- ```
- The delimiter may be overridden with stringify as well:
- ```javascript
- Qs.stringify({ a: 'b', c: 'd' }, { delimiter: ';' });
- // 'a=b;c=d'
- ```
- Finally, you can use the `filter` option to restrict which keys will be included in the stringified output.
- If you pass a function, it will be called for each key to obtain the replacement value. Otherwise, if you
- pass an array, it will be used to select properties and array indices for stringification:
- ```javascript
- function filterFunc(prefix, value) {
- if (prefix == 'b') {
- // Return an `undefined` value to omit a property.
- return;
- }
- if (prefix == 'e[f]') {
- return value.getTime();
- }
- if (prefix == 'e[g][0]') {
- return value * 2;
- }
- return value;
- }
- Qs.stringify({ a: 'b', c: 'd', e: { f: new Date(123), g: [2] } }, { filter: filterFunc })
- // 'a=b&c=d&e[f]=123&e[g][0]=4'
- Qs.stringify({ a: 'b', c: 'd', e: 'f' }, { filter: ['a', 'e'] })
- // 'a=b&e=f'
- Qs.stringify({ a: ['b', 'c', 'd'], e: 'f' }, { filter: ['a', 0, 2] })
- // 'a[0]=b&a[2]=d'
- ```
- ### Handling of `null` values
- By default, `null` values are treated like empty strings:
- ```javascript
- Qs.stringify({ a: null, b: '' });
- // 'a=&b='
- ```
- Parsing does not distinguish between parameters with and without equal signs. Both are converted to empty strings.
- ```javascript
- Qs.parse('a&b=')
- // { a: '', b: '' }
- ```
- To distinguish between `null` values and empty strings use the `strictNullHandling` flag. In the result string the `null`
- values have no `=` sign:
- ```javascript
- Qs.stringify({ a: null, b: '' }, { strictNullHandling: true });
- // 'a&b='
- ```
- To parse values without `=` back to `null` use the `strictNullHandling` flag:
- ```javascript
- Qs.parse('a&b=', { strictNullHandling: true });
- // { a: null, b: '' }
- ```