Less than or equal (<=) - JavaScript 编辑

The less than or equal operator (<=) returns true if the left operand is less than or equal to the right operand, and false otherwise.

The source for this interactive example is stored in a GitHub repository. If you'd like to contribute to the interactive examples project, please clone https://github.com/mdn/interactive-examples and send us a pull request.

The source for this interactive example is stored in a GitHub repository. If you'd like to contribute to the interactive examples project, please clone https://github.com/mdn/interactive-examples and send us a pull request.

Syntax

 x <= y

Description

The operands are compared using the Abstract Relational Comparison algorithm. See the documentation for the Less than operator for a summary of this algorithm.

Examples

String to string comparison

console.log("a" <= "b");     // true
console.log("a" <= "a");     // true
console.log("a" <= "3");     // false

String to number comparison

console.log("5" <= 3);       // false
console.log("3" <= 3);       // true
console.log("3" <= 5);       // true

console.log("hello" <= 5);   // false
console.log(5 <= "hello");   // false

Number to Number comparison

console.log(5 <= 3);         // false
console.log(3 <= 3);         // true
console.log(3 <= 5);         // true

Number to BigInt comparison

console.log(5n <= 3);        // false
console.log(3 <= 3n);        // true
console.log(3 <= 5n);        // true

Comparing Boolean, null, undefined, NaN

console.log(true <= false);  // false
console.log(true <= true);   // true
console.log(false <= true);  // true

console.log(true <= 0);      // false
console.log(true <= 1);      // true

console.log(null <= 0);      // true
console.log(1 <= null);      // false

console.log(undefined <= 3); // false
console.log(3 <= undefined); // false

console.log(3 <= NaN);       // false
console.log(NaN <= 3);       // false

Specifications

Specification
ECMAScript (ECMA-262) The definition of 'Relational operators' in that specification.

Browser compatibility

BCD tables only load in the browser

See also

• Greater than operator
• Greater than or equal operator
• Less than operator