使用javascript搜索字符串中的字符

function searchCharacter(str, char) {
  var index = str.indexOf(char);
  var positions = [];
  
  while (index !== -1) {
    positions.push(index);
    index = str.indexOf(char, index + 1);
  }
  
  return positions;
}

var str = "Hello World";
var char = "o";
var positions = searchCharacter(str, char);
console.log(positions); // [4, 7]

function searchCharacter(str, char) {
  var regex = new RegExp(char, "g");
  var positions = [];
  var match;
  
  while ((match = regex.exec(str)) !== null) {
    positions.push(match.index);
  }
  
  return positions;
}

var str = "Hello World";
var char = "o";
var positions = searchCharacter(str, char);
console.log(positions); // [4, 7]

function searchCharacter(str, char) {
  var positions = [];
  
  for (var i = 0; i < str.length; i++) {
    if (str[i] === char) {
      positions.push(i);
    }
  }
  
  return positions;
}

var str = "Hello World";
var char = "o";
var positions = searchCharacter(str, char);
console.log(positions); // [4, 7]