Two "=" characters in a string-CodePudding

How to check in javascript if in the string there are two "=" symbols and to throw a mistake (beacuse for example 1 =2=3 is wrong but 1 2=3 is right)

CodePudding user response：

function validateText() {
  const text = document.getElementById('text').value;
  if ((text.match(/=/g)?.length || 0) < 2) {
    document.getElementById('result').innerHTML = "Valid";
  } else {
    document.getElementById('result').innerHTML = "Invalid";
  }
}

<textarea id="text"></textarea>

<button onclick=validateText()>Validate</button>

<p id="result"></p>

CodePudding user response：

var input_true = '1   = 2    3';
var input_false = '1   = 2   = 3';
var success = /^[^=]*=[^=]*$/.test(input_true);      // pass
var not_success = /^[^=]*=[^=]*$/.test(input_false); // fails

CodePudding user response：

Write a little function that uses a regex to test for this.

function tester(str) {
  return str.match(/=/g).length === 1;
}

console.log(tester('='));
console.log(tester('Bob=='));
console.log(tester('Bob='));
console.log(tester('=Bob=='));