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This article will explain in detail how to achieve the random CAPTCHA function of js. The editor thinks it is very practical, so I share it with you as a reference. I hope you can get something after reading this article.

Create a function: randomly generate numbers and operators

Function randomInt (x) {

Var code = Math.floor (Math.random () * x)

Return code

}

Generate the addition and subtraction verification code:

Call randomInt () in this function, if it is subtraction, determine whether the result is less than 0, then continue to be random, otherwise enter the page, use result to save the results.

Var code,result

Function createCode () {

Var isTrue = true

While (isTrue) {

Var first = randomInt (30)

Var last = randomInt (30)

Var opt= randopt (2)

If (opt==0) {

Result = first+last

Code = first+' +'+ last

} else {

Result = first-last

Code = first+'-'+last

}

If (result > = 0) {

IsTrue = false

}

}

Return "" + code+ ""

}

Comparison and verification

Get the number entered by the user and compare it; the function is as follows:

Function checkcode (code1) {

If (code1==String (result)) {

Return true

} else {

Return false

}

}

All the functions encapsulated above can be simply called, and the final display effect is as follows:

Of course, the page effect needs to be drawn with html,css.

This is the end of this article on "how to achieve random CAPTCHA function in js". I hope the above content can be of some help to you, so that you can learn more knowledge. if you think the article is good, please share it for more people to see.

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