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SyntaxError: Unexpected token

JavaScript "unexpected token" 

SyntaxError: Unexpected token ';' (V8 )
SyntaxError: Unexpected identifier 'x' (V8 )
SyntaxError: Unexpected number (V8 )
SyntaxError: Unexpected string (V8 )
SyntaxError: Unexpected regular expression (V8 )
SyntaxError: Unexpected template string (V8 )

SyntaxError: unexpected token: identifier (Firefox)
SyntaxError: expected expression, got "x" (Firefox)
SyntaxError: expected property name, got "x" (Firefox)
SyntaxError: expected target, got "x" (Firefox)
SyntaxError: expected meta, got "x" (Firefox)
SyntaxError: expected rest argument name, got "x" (Firefox)
SyntaxError: expected closing parenthesis, got "x" (Firefox)

SyntaxError

js
for (let i = 0; i < 5,; ++i) {
  console.log(i);
}
//  SyntaxError: expected expression, got ';'

js
for (let i = 0; i < 5; ++i) {
  console.log(i);
}

if

js
function round(n, upperBound, lowerBound) {
if (n > upperBound) || (n < lowerBound) { // 
    throw new Error(`Number ${n}  ${upperBound}  ${lowerBound} `);
  } else if (n < (upperBound + lowerBound) / 2) {
    return lowerBound;
  } else {
    return upperBound;
  }
} // SyntaxError: expected expression, got '||'

|| ||

js
function round(n, upperBound, lowerBound) {
  if ((n > upperBound) || (n < lowerBound)) {
    throw new Error(
      `Number ${n}  ${upperBound}  ${lowerBound} `,
    );
  } else if (n < (upperBound + lowerBound) / 2) {
    return lowerBound;
  } else {
    return upperBound;
  }
}

js
const MyComponent = {
  mounted: {
    document.getElementById("app").classList.add("loaded");
  }
}

document . JavaScript {} : mounted

js
const MyComponent = {
  mounted() {
    document.getElementById("app").classList.add("loaded");
  }
}

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    63. SyntaxError: missing } after function body
    64. SyntaxError: missing } after property list
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    66. SyntaxError: missing formal parameter
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    81. SyntaxError: return not in function
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    83. SyntaxError: unterminated string literal
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