Performance comparison analysis code for JavaScript parsing Json string_json

The methods used during parsing are generally eval or new function, and currently IE8 and Firefox3.1 have built-in native JSON objects (it is said that there will be a certain performance improvement). So how do we choose from these three methods (due to performance issues, parsing implemented in JavaScript is not considered) when we actually use it? Faced with numerous browsers, which method has the best performance?

1. Testing method

1. First specify the number of tests and JSON string

Copy the code The code is as follows:

var count = 10000, o = null, i = 0, jsonString = '{"value":{"items": [ {"x":1,"y":2,"z":3}, {"x":1,"y":2,"z":3}, {"x":1,"y" :2,"z":3}, {"x":1,"y":2,"z":3}, {"x":1,"y":2,"z":3}] },"error":null}';

2. Loop analysis and record time

eval

Copy code The code is as follows:

var beginTime = new Date();
for ( i = 0; i < count; i ) {
o = eval( "(" jsonString ")" );
}
Console.output( "eval:" ( new Date() - beginTime ) );

new Function

Copy code The code is as follows:

var beginTime = new Date();
for ( i = 0; i < count; i ) {
o = new Function( "return " jsonString )();
}
Console.output( "new Function:" ( new Date() - beginTime ) );

native

Copy code The code is as follows:

if ( typeof JSON !== "undefined" ) {
var beginTime = new Date();
for ( i = 0; i < ; count; i ) {
o = JSON.parse( jsonString ); }
Console.output( "native:" ( new Date() - beginTime ) );
} else {
Console .output( "native:not support!" );
}

2. Test object

Choose the current mainstream browser (not considered Maxthon and other shells), including IE6, 7, 8, Firefox2, 3, 3.1, Chrome, Opera and Safari3, 4.

3. Test environment

T9300 CPU 4G RAM Windows2003, IE8 uses Vista environment, IE7 is in another working machine (2G CPU 2G RAM Windows2003 ), considering that the main purpose is to test the performance of the browser client, the error in the results should be acceptable.

4. Test results
Copy code The code is as follows: