trim

let stringValue = "   hello world   ";
let trimmedStringValue = stringValue.trim();
console.log(stringValue);           // "   hello world "
console.log(trimmedStringValue);   // "hello world"

正则替换

去除字符串内所有的空格：str = str.replace(/\s/g,””);
去除字符串内两头的空格：str = str.replace(/^\s|\s$/g,””);
去除字符串内左侧的空格：str = str.replace(/^\s/,””);
去除字符串内右侧的空格：str = str.replace(/(\s*$)/g,””);

var str = " 6 6 ";
var str_1 = str.replace(/\s*/g,"");
console.log(str_1); //66
var str = " 6 6 ";
var str_1 = str.replace(/^\s*|\s*$/g,"");
console.log(str_1); //6 6//输出左右侧均无空格
var str = " 6 6 ";
var str_1 = str.replace(/^\s*/,"");
console.log(str_1); //6 6 //输出右侧有空格左侧无空格
var str = " 6 6 ";
var str_1 = str.replace(/(\s*$)/g,"");
console.log(str_1); // 6 6//输出左侧有空格右侧无空格