js简易计算器

<meta charset="utf-8">
<style>
	body{ background-color:#f9f9f9;}
	button{ width:30px; height:30px; margin-top:3px;}
	input[type=text]{ padding:5px; font-size:16px;}
</style>

<input type="text" id="input2" />
<input type="button" onclick="sure();" value="计算" />
<input type="button" onclick="clearInput();" value="清空" />
<br />
<button onclick="get(this.value);" value="1">1</button>
<button onclick="get(this.value);" value="2">2</button>
<button onclick="get(this.value);" value="3">3</button>
<button onclick="get(this.value);" value="4">4</button>
<button onclick="get(this.value);" value="5">5</button>
<br />
<button onclick="get(this.value);" value="6">6</button>
<button onclick="get(this.value);" value="7">7</button>
<button onclick="get(this.value);" value="8">8</button>
<button onclick="get(this.value);" value="9">9</button>
<button onclick="get(this.value);" value="0">0</button>
<br />
<button onclick="get(this.value);" value="+">+</button>
<button onclick="get(this.value);" value="-">-</button>
<button onclick="get(this.value);" value="*">*</button>
<button onclick="get(this.value);" value="/">/</button>
<button onclick="get(this.value);" value=".">.</button>

<script>
function clearInput(){
	input2.value = '';
}

function get(x) {
	input2.value += x; 
} 

function sure() {
	input2.value = eval(input2.value);
};
</script>

运行结果