How to compare two strings in JS

String comparison in JavaScript

Greater than (>), less than (<) operator

javascript string in When performing a greater than (less than) comparison, the comparison will be based on the ASCII value code of the first different character. When the number (number) is compared with the string (string), the number (number) will be forcibly converted into a character. string(string) and then compare.

Code:

(function(){
    console.log('13'>'3'); // 输出：false
    console.log(5>'6');  // 输出： false
    console.log('d'>'ABDC') // 输出： true
    console.log(19>'ssf') // 输出 false
    console.log('A'>'abcdef') // 输出 false
})()

Equality (==), strict equality (===) operator

When performing equality (==) operation comparison, if one side is a character and the other side is a number, the string will be converted into a number first and then compared; for strict equality (===), it will not be performed. Type conversion will compare types for equality. Note that NaN is false when compared with any value

(function(){
   console.log('6'==6) // true
   console.log('6'===6) // false
   console.log(6===6) // true
   console.log('abc'==2) // false
   console.log('abc'=='abc') // true
   console.log('abc'==='abc') // true
})()

3. Equality and strict equality comparison of some special values

(function(){
    console.log(null==undefined) // 输出：true
    console.log(null===undefined) // 输出：false
    console.log(null===null) // 输出：true
    console.log(undefined===undefined) // 输出：true
    console.log(NaN==undefined) // 输出：false
    console.log(NaN==null)  // 输出：false
    console.log(NaN==NaN)  // 输出：false
    console.log(NaN===NaN)  // 输出：false
})()

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