JS using eval () to create variables dynamically _javascript tips

This example describes the way JS uses eval () to create variables dynamically. Share to everyone for your reference, specific as follows:

One, what is the eval () function?

The Eval_r () function computes a string and executes the JavaScript code in it.

Ii. How to define variables dynamically?

Since Eval () is able to compute a string, why not convert the definition variable to a string, and then put it into the Eval_r () function to execute, as follows:

var definestr = "var number_" +i.tostring ();
Eval_r (DEFINESTR);

This defines a variable, and you can set the debugger trace to debug to see if the number variable is defined successfully.

If the I value is 1, then the dynamic variable is number_1

The following can be assigned a value in this form:

Eval_r ("Number_" +i.tostring () + "= 120;");

This assigns a value of 120 to its variable number_1.

But there is absolutely no way to write this:

Eval_r ("Number_" +i.tostring ()) = 120

This writing is in the wrong way.

This type of writing in IE is not workable, you need to use Executescript (string) to perform, judged as follows:

if (window.executescript)
{
//ie browser
window.executescript (DEFINESTR);
} else
{
//chrome, Firefox, etc. non ie browser
window.eval_r (DEFINESTR);
}

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I hope this article will help you with JavaScript programming.