Node.js中的setImmediate()与process.nextTick

简单说,process.nextTick是在当前代码执行完毕后立即执行,setImmediate是加入到轮询,空闲后立即执行.

测试结论:

process.nextTick >> setTimeout(handler,0) , setImmediate >> setTimeout(handler, n)

注: setTimeout(handler,0) 与 setImmediate的顺序未深入比较.

上代码：

var a = 1;console.log(a);setImmediate(function() {    console.log('-----------setImmediate----------');    console.log(a);});a=2;setTimeout(function() {    console.log('-----------settimeout 0----------');    console.log(a);},0);a=3;setTimeout(function() {    console.log('-----------settimeout 2000----------');    console.log(a);},2000);a=4;setTimeout(function() {    process.nextTick(function() {        a=6;        console.log('-----------process.nextTick----------');        console.log(a);    });    console.log('-----------settimeout 1000----------');    console.log(a);},1000);a=5;process.nextTick(function() {    console.log('-----------process.nextTick----------');    console.log(a);});

执行结果:

1-----------process.nextTick----------5-----------settimeout 0----------5-----------setImmediate----------5-----------settimeout 1000----------5-----------process.nextTick----------6-----------settimeout 2000----------6