How to detect decimals in javascript

Javascript method to detect decimals: 1. Use indexOf(), syntax "String(num).indexOf(".")", if the return value is greater than "-1", it is a decimal. 2. Use regular expressions, the syntax "var rep=/[\.]/;rep.test(num)".

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

Javascript method to detect whether it is a decimal

Method 1: Use the indexOf() method

Idea:

Decimals have a decimal point ".". We can use the indexOf() method to determine the position of the decimal point to determine whether it is a decimal. If the return value of the indexOf() method >-1 is a decimal.

Implementation code:

function isDot(num) {
	if(String(num).indexOf(".")>-1){
		console.log("是小数");
	}
	else{
		console.log("不是小数");
	}
}
isDot(121.121);//含有小数点
isDot(454654);//不含小数点

Output result:

是小数
不是小数

Method 2: Use regular expressions to determine whether it is a decimal

function isDot(num) {
	var rep=/[\.]/;
	if(rep.test(num)){
		console.log("是小数");
	}
	else{
		console.log("不是小数");
	}
}
isDot(121.121);//是小数
isDot(454.654);//是小数
isDot(454654);//不是小数

Output result:

是小数
是小数
不是小数

[Recommended learning: javascript advanced tutorial]

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