Use el expression to determine if it is not empty

This time I will bring you the non-empty judgment of el expression. What are the precautions for using el expression to judge non-empty? The following is a practical case, let's take a look.

Scenario:

After the page jumps, use spring mvc to pass a json object to the front-end page. After getting it in js, Do processing.

Returned json object:

{"nodes":[{"contactmobile":"15922208502","orderno":"XNH31918062989476864"},{"id":"12198","group":"11","content":"把考虑考虑","modelname":"Company"}],"links":[{"target":"12198","id":"15016","relationType":"公司","source":"12194"}]}

var graph; 
var flag = "${empty jsonData}"; 
if(flag!="true"){ 
  graph = eval('(' + '${jsonData}' + ')'); 
};

There is a note here:

When using el expressions in js, be sure to use quotation marks. If the returned json contains double quotes, then use single quotes to surround the el expression, otherwise, use double quotes.

In addition, pay attention to the writing method of using the eval function to convert the json string into an object.

I believe you have mastered the method after reading the case in this article. For more exciting information, please pay attention to other related articles on the php Chinese website!

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