The less than operator (
<
) returns
true
if the left operand is less than the right operand, and
false
否则。
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x < y
The operands are compared using the Abstract Relational Comparison algorithm, which is roughly summarised below:
Symbol.ToPrimitive
.
true
and
false
are converted to 1 and 0 respectively.
null
is converted to 0.
undefined
is converted to
NaN
.
NaN
if they do not contain numeric values.
NaN
, the operator returns
false
.
console.log("a" < "b"); // true
console.log("a" < "a"); // false
console.log("a" < "3"); // false
console.log("5" < 3); // false
console.log("3" < 3); // false
console.log("3" < 5); // true
console.log("hello" < 5); // false
console.log(5 < "hello"); // false
console.log("5" < 3n); // false
console.log("3" < 5n); // true
console.log(5 < 3); // false console.log(3 < 3); // false console.log(3 < 5); // true
console.log(5n < 3); // false console.log(3 < 5n); // true
console.log(true < false); // false console.log(false < true); // true console.log(0 < true); // true console.log(true < 1); // false console.log(null < 0); // false console.log(null < 1); // true console.log(undefined < 3); // false console.log(3 < undefined); // false console.log(3 < NaN); // false console.log(NaN < 3); // false
| 规范 |
|---|
|
ECMAScript (ECMA-262)
The definition of 'Relational operators' in that specification. |
| Desktop | Mobile | Server | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Less than (
a < b
)
|
Chrome 1 | Edge 12 | Firefox 1 | IE 3 | Opera 3 | Safari 1 | WebView Android 1 | Chrome Android 18 | Firefox Android 4 | Opera Android 10.1 | Safari iOS 1 | Samsung Internet Android 1.0 | nodejs 0.1.100 |
完整支持