How does javascript determine whether the data entered in the control is a numeric type?

This article will explain in detail how javascript judges the data entered in the control as a numerical type. 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.

Judgment method: 1, use "input control object .value" statement to obtain user input data; 2, use "var re = / ^ [0-9] +.? [0-9] * /" statement to define regular expression object; 3, use "re.test (input data)" sentence to judge whether the input data is a numerical type.

The operating environment of this tutorial: windows7 system, javascript1.8.5 version, Dell G3 computer.

Javascript determines that the data entered in the control is a numeric type.

First, you need to use the value property to get the value of the input control

Then the regular expression and the test () function are used to determine whether the input data in the control is a numeric type.

Implementation code:

Judge type function my (id) {return document.getElementById (id);} my ("btn"). Onclick = function () {var val = my ("num"). Value; var re = / ^ [0-9] +. [0-9] * / / / determine whether the string is numeric / / determine whether the string is a positive integer / [1 − 9] + [0 − 9] ∗] ∗ / if (re.test (val)) {console.log ("input is a numeric type");} else {console.log ("input is not a numeric type, please re-enter") }}

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