res.send
和res.json
之间的实际区别是什么,因为两者似乎都执行相同的响应客户端的操作。
The methods are identical when an object or array is passed, but res.json()
will also convert non-objects, such as null
and undefined
, which are not valid JSON.
The method also uses the json replacer
and json spaces
application settings, so you can format JSON with more options. Those options are set like so:
app.set('json spaces', 2);
app.set('json replacer', replacer);
And passed to a JSON.stringify()
like so:
JSON.stringify(value, replacer, spacing);
// value: object to format
// replacer: rules for transforming properties encountered during stringifying
// spacing: the number of spaces for indentation
This is the code in the res.json()
method that the send method doesn't have:
var app = this.app;
var replacer = app.get('json replacer');
var spaces = app.get('json spaces');
var body = JSON.stringify(obj, replacer, spaces);
The method ends up as a res.send()
in the end:
this.charset = this.charset || 'utf-8';
this.get('Content-Type') || this.set('Content-Type', 'application/json');
return this.send(body);
res.json
eventually calls res.send
, but before that it:
json spaces
and json replacer
app settingsLooking in the headers sent...
res.send uses content-type:text/html
res.json uses content-type:application/json
edit: send actually changes what is sent based on what it's given, so strings are sent as text/html, but it you pass it an object it emits application/json.
res.json
forces the argument to JSON. res.send
will take an non-json object or non-json array and send another type. For example:
This will return a JSON number.
res.json(100)
This will return a status code and issue a warning to use sendStatus.
res.send(100)
If your argument is not a JSON object or array (null,undefined,boolean,string), and you want to ensure it is sent as JSON, use res.json
.
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