JavaScript uses Eval to parse JSON points of attention

For a JSON-formatted string, you need to be aware of the parentheses when you use eval to convert a string to a JSON object. As shown below:

<script type= "Text/javascript" >
var data = ' {root:[{name: "1", Value: "0"},{name: "6101", Value: "Beijing"},{name: "6102", Value: "Tianjin"}]} ';
var dataobj_1 = eval (data);
var dataobj_2 = eval ("+ Data +"));
Console.info (dataobj_1);
Console.info (dataobj_2);
</script>

The results of this code are as follows:

The results of this code are as follows:

Figure 1: Code Run results

The results appear as above because the eval itself can parse and run the code in the string. Since JSON starts and ends in {}, it is treated as a block of statements in JS, so it is imperative to convert it to an expression without being treated as a block of statements. The purpose of parentheses is to force the function to convert an expression in parentheses to an object when it is processed instead of executing it as a statement.

It's easy to accept that this is a problem on the web, but it's worth noting.