How to convert string to boolean type in javascript

Javascript method to convert a string to a boolean type: 1. Use double logical negation "!!" and syntax "!! String"; 2. Use the Boolean() function to force the value to be converted to Boolean value, syntax "Boolean(String)".

The operating environment of this tutorial: windows7 system, javascript version 1.8.5, Dell G3 computer.

There are 2 common ways for JavaScript to convert values ​​to Boolean values:

• Use double logical not

• Use Boolean () Function

Method 1: Use double logical NOT

A logical NOT operator! can convert the value is a Boolean value and negated, two logical NOT operators can convert the value to the correct Boolean value.

console.log(!!0);  //返回false
console.log(!!1);  //返回true
console.log(!!"");  //返回false
console.log(!!NaN);  //返回false
console.log(!!null);  //返回false
console.log(!!undefined);  //返回false
console.log(!![]);  //返回true
console.log(!!{});  //返回true
console.log(!!function(){});  //返回true

Method 2: Use the Boolean() function

Use the Boolean() function to force the value to be converted to a Boolean value.

console.log(Boolean("0"));  //返回true
console.log(Boolean("1"));  //返回true
console.log(Boolean(""));  //返回false

Attachment: Convert common values ​​to Boolean values

##1true0false##truefalse""##undefined falsenullfalseNaNfalseInfinitytrue##[Recommended learning: javascript advanced tutorial】

Convert common values ​​to Boolean values

true
false
false

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