JSFiddle - React, Tailwind, and code Playground

HTML

<form>
<input type="number" step="any" oninput="validate(this)" />
    <input type="submit" value="ok" />
</form>

JavaScript

function validate(input){
    var number = parseFloat(input.value);
    if( number == input.value && input.value.length <= number.toFixed(6).length ){
         console.log( 'valid' );   
    }
    else {
         console.warn( 'invalid' );   
    }
}